Monday, November 13, 2017

Blade Damage - Differences In Blade Damage

I receive more questions about blades than anything. The inquiries are varied but more often than not come down to constructing a fight scene. With any fight, movements are determined by the intended damage. Even if that damage isn’t inflicted, the intention tells how the aggressor is moving as well as the defender.

Because that damage is so important, we need to understand it. Over the next few weeks, we are going to examine damage caused by blades. Specifically:
* Damage by different blades 
* Vital strike points 
* Wound appearance 
* A wound’s impact on the body
* After care

In case you’re wondering, yes, the wound appearance one will include photos. You’ve been warned or pleasantly informed however you want to think of it.

First off, let’s consider damage by different blades. There’s an idea that certain blades are more damaging than others. But, in truth, a wound two inches wide and four inches deep has the same consequences regardless of what caused it. So, in that respect, a sword is no more deadly than a knife.  

I can hear what you’re thinking, a sword is deadlier because it can go way deeper. Well, yes, it can. But remember, the advantage of a sword over a knife is reach. To drive a sword deep you will have to get closer to your opponent. And, though stabbed, that opponent can absolutely retain their ability to strike back for several minutes. We’ll look at that more closely in a few weeks. For now, know a deep plunge isn’t necessarily the wisest move. Also, the deeper the stick, the harder the hold the body will have on the inserted blade. The body has an internal vacuum. It wants to pull in whatever compromises that. 

Also, as important as the wound dimensions is the location. One can be stabbed with a pen knife in the chest many times and survive. I knew a young lady that was stabbed at least sixteen times with a small knife in her chest and back and survived, praise God. Had wounds of the same dimension been created on her neck, that wouldn't have been the case.  

Here’s a video on differences in damage caused by different blades. It also addresses why some blade shapes are more suitable for stabbing and touches on the physics of it. If you’ve read the post on size disparity, you’ll remember the importance of mass x acceleration.

Until the next round and, get blood on your pages.

JUST KIDDING! I think we all knew by the post thumbnail that there would be a link to this most epic fight. Writers, we can learn a lot from the Black Knight. We are, all too often, piƱatas with pens. We take our share of hits from agents, editors and publishers. "Readers" leave one star reviews. I put that in quotation marks because you know good and well some of those people never read the book. Never mind all the folks who don't take what we do seriously.

We have to find the strength to stand tall, if we can stand at all, and proclaim, "'Tis but a scratch!"

NOW...until the next round at, my steadfast, stalwart, readers, get blood on your pages.

Wednesday, November 1, 2017

FightWriter - Jonathan Clay: Fighting in Zero-G

This week's FighterWriter, Jonathan Clay, asks: How would hand to hand combat change in
a zero-g environment (say, on the ISS)?

Good question. Any time I explain how something works, or doesn’t work, I try my best to use science for several reasons. One, science is something to which we can all relate. You don't have to know a thing about fighting to understand the science of fighting. Two, it doesn’t change. Fighting is fickle. Science is stubborn. Three, Science is, like, so much smarter than me. Seriously, she knows about physics and stuff which most fighting totally is. That said, if you have magic in your manuscript, some of this may not apply. If that’s the case, your reader should be aware of the physical laws of your world. 

Ok, let’s put on our Newton pants and look at his laws of motion.

Law One: An object at rest tends to stay at rest. An object in motion tends to stay in motion.

Things on earth slow down because of the opposing force of gravity. On the ISS, however, if you push yourself off of a wall you will keep going until you hit something. And, you better hope you hit something because if you don’t, you will just keep going until Jesus comes for you. How can you use that to your advantage in a fisticuffs? Push your opponent. It won’t take much. A little nudge could send them off into oblivion if they aren’t anchored in some way. If you do hit them, they will propel away from you until something stops them. Which is all well and good until that third law comes into play.

Law Three: For every action, there is an equal and opposite reaction.

If I hit you, I am, in turn, pushing myself away from you with that same amount of force. That puts me in a real pickle. And before you say, “oh, no biggie, there’s a wall behind my character,” remember that the character will hit that wall with a force equal to that of their punch. And, if their momentum is circular, as with a hook, the character might end up spinning until they hit something…with a force equal to their punch. 

The way to work around the first law also helps with the third. Your character would hold on to their opponent. And, they’d probably do well to grasp the combatant on the center line of their body – say, the chest of their clothing – as it would give your character a point of reference for their strike. When the body starts spinning, your character could get disoriented. Their hand below their combatant's face would guide their aim no matter how their own body is moving.
But, I tell ya, if it were me, I wouldn’t punch at all because of the second law of motion.

Law Two: Force = mass x acceleration. (Law One explains that an object at rest tends to stay at rest. Law two shows how that resting state changes when the object is subjected to an external force.)

I only know how to punch on earth. And, on earth, I am able to create force for my strike by getting as much of my mass and speed into the equation (literally) as possible. To get the mass of my body behind my punch as well as create acceleration, I need rotation in my upper body. That rotation is a result of torque in my hips. That torque (twisting motion) is given speed as well as stability by the pivot of my feet on the ground.  

My feet remain anchored to the ground while pivoting because of friction. I have stepped in sweat before, pivoted and hit the mat because that liquid inhibited my friction. It took away my hold on the floor and the torque in my hips set me off balance. That friction is crucial to the entire movement that creates force in a punch. And the thing about friction is that it needs gravity.  

So, I personally can’t see how, from free floating, a punch in zero-g would have as much force for the simple fact that it doesn't have any sort of anchor. Now, by propelling off of a wall you could create acceleration to go with your mass and create a ton of force with that punch – which will send you flying let's not forget. But, again, from free floating, I just don't see how it's scientifically doable.

Also, punching is a problem because it brings in momentum. It would send me and my opponent banging around against the walls and all the equipment in the room. I could feasibly be knocked out by whatever we propel ourselves into. It takes next to no effort to move as you can see in this video. Imagine how you would move with a bit of muscle.

There's also the issue of blood from a busted nose or split forehead etc. Liquids in space are "squirrely." They move around in bubbles so you have a bit of a traveling mess.

Instead, I would employ a choke. I'm not talking about a strangle hold. I mean capturing the neck in such a way that blood flow is impeded which leads to unconsciousness. At the same time, I’d want to isolate their legs because they would likely kick out of panic. The kick could create momentum which might propel us and cause me to to hit something. If I can manage to be anchored to something while choking them, the legs wouldn't be an issue.

If I chose the right sort of choke, I wouldn’t need to worry about guarding my own neck as my body position would make it difficult or impossible for them to attack me. But, again, their legs could cause some momentum issues. I’d want to wrap those babies up with my own legs.

This is my favorite choke, my go-to. Probably what I would use. It happens at 1:13 on the video.

I hope that gives you all some ideas for your work. Again, the physical laws of your created world may differ. Plus, spacecrafts in movies and TV all seem to work out an artificial gravity so zero-g isn't an issue. I'm not sure how they do that but they all do with the premise that we will accept the fact and we do! 

But, every now and then, movies like Inception embrace the concept of "compromised gravity". It wasn't zero-g as much as moving-g! Here's a behind the scenes look at how they did it.  

Until the next round at FightWrite, get blood on your pages.

Wednesday, October 18, 2017

Featured FightWriter - S. E. M. Ishida - How Realistic Are Martial Arts in a Real Fight

Our question this week is from FightWriter S. E. M. Ishida:

I'm curious to know how martial arts fighting styles compare to actual fighting. I recently started learning a martial art, and I hope that learning it will help me when I write fight scenes. Are certain martial arts/fighting styles more "realistic" than others? Do you have any that you recommend?

First, every martial art is best for what it is designed to do. Some meet power with power. Some use the opponent’s power and momentum against them. Some are meant to spare the hands and some were designed around weaponry to spare the entire body. But, all of them are great to learn. Every single one will make you stand a bit taller and give you more confidence which is key in a whole lot of things including writing.

Now that I've clearly stated that all martial arts are great and there is no reason for anyone to send me long emails for not giving props to their particular art, I want to look back at your question and raise one of my own. What do you mean by an “actual fight?” Fights change depending upon the setting. A fight in a
bar will look different than one on the street. The former will have a bit more bravado and hints of social order meaning there will be some things that likely won’t be done that would absolutely be done were the fight to go to the parking lot. 

What’s the difference between inside the bar and outside in the parking lot? Witnesses. Yes, in a bar you may have weapons drawn, bottles broken and used. But again, there will be people who can say what they saw you do. For that same reason, a person may want the violence they inflict to look tough. They will throw a big haymaker punch rather than gouge an eye. And, as well, there may be a crowd which might inhibit movement. You aren’t as likely to shoot if perhaps you could hit your buddies who are brawling around you.

The latter, a street fight, is going to be far more brutal and primal. There is zero social order. It’s straight up Lord of the Flies. Weapons will be drawn/wielded and every manner of attack will be fair game. People bite, tear body parts and claw at eyes. They stomp heads, kick ribs and pull out so much hair hematomas form on the scalp.  

Which martial art is designed to combat that sort of violence? Well, that’s a toughie. There are a few that work off the assumption that the poop has hit the fan with extreme prejudice. None, however, assure that you will have the exact moves to handle every single scenario. But, you don’t have to in order to productively defend.

So, again, “realistic fight” is a very broad term. Like any great story, how a fight plays out in real life depends upon the setting. Will learning karate (just using that as an example) help you write that Victorian fight scene? Well, yeah, it can, if you spar.The most important thing you can do in any martial art to better write fight scenes (as well as learn to defend yourself) is to spar.  

Sparring will help you better understand how the body moves and reacts to attack. You know that when a strike comes from the right, the rest of the body generally does ___. And, if you want to advance you will have to do so defensively because any time you attack, you open yourself up in kind.

It also helps you understand body positioning. Some moves feed into others because the body movement of the first sets up or lends itself to the second. And, just as well, some moves don't work together. You learn that by trial and error in sparring. Oh man, in your head, you come up with amazing sequences! Then you get on the mat, give it a go and realize that to do move two, you should be facing left but move one left you facing the right.

Lastly, by sparring, you will learn that sometimes you target an area not so much to make contact with that area but to get your opponent to move a certain way. That particular movement will open up the target you really wanted but your partner had been defending. You strike at the belly to expose the neck. You strike the left side to open the right.  

Now, will doing jiujitsu make you better at writing a fist fight scene? No, it won't. If you want something specific, you will need to study that specific thing. But, no worries, whatever gaps you feel you have in your fight training can be filled in right here! TA-DA!

So, in summary, whatever martial art you do is awesome. All of them make you a better human. If you want it to really impact your fightwriting, you need to spar as that teaches things you can't learn in other way. And, finally, what you don't learn in the gym/dojo/kwoon/etc. you can learn here. If I haven't posted on it, ask me about it and I will.

Thank you for your question, Sarah. Whatever martial art you are doing, keep doing it! I’ve never heard anyone say, “dang, I wish I hadn’t gotten more physically active, learned a skill, improved my self esteem and self discipline and had so much fun! Ugh, it’s the WORST!”  

Until the next round at, get blood on your pages.

Tuesday, October 10, 2017

FightWriters Luke Scott & Johne Cook: Chop vs Punch and Bringin' a Knife to a Gun Fight

This is the second week in a series where we will focus solely on FightWriter questions. In this round, we compare chops and punches and bring a knife to a gun fight.

Luke Scott: Why don't you see karate chop strikes in MMA? They were great for board breaking when I was a kid. Is it just a bone breakage issue or does a punch carry superior force?

Alrighty, fightwriters. First, the knife edge hand strike is an effective strike. A skilled martial artist could deliver one and render a person unconscious or kill them. Yes, really.  

So, why don’t you see them in MMA? I have several reasons. Here we go:

One: MMA is a sport and as such, it has rules. Any strike to the groin, back of head/spine and neck are illegal. Knife edge strikes work very well in those places.

Two, there is a greater chance of injuring the hand. All fighters who use their hands to strike have their hands wrapped before they fight because like or not, our hands weren't made for punching! The wrap pulls the bones of the hands together so that the impact of their strike is dispersed over all the bones rather than one or two which can result in what is known as a boxer’s break. I will do a post on that at some point. 

Because the contact of knife edge chop is to the side of the
Floyd Mayweather post Canelo fight. 
hand, you have a great deal of force impacting the side of a single bone. The odds of the fighter breaking their hand is much greater because a knife edge is meant to be decisive rather than repetitively thrown hundreds of times in 3 to 5, five minute rounds. 

Three, a punch is driven by the torque and rotation of the body. A chop, and hammer fist as well, aren’t driven. Their momentum is with a swing which positions the body differently. With every driven punch, you guard your face. The shoulder of the striking hand comes up to protect that side of the jaw. With a standard chop, it’s darn near impossible to protect the chin and still have momentum in that strike. Thus, the jaw is open which makes one more vulnerable to a knock out as explained in my post on knock out punches.

But, you can absolutely pull off certain strikes, leave your jaw open and be fine. You can see that in the pic here with Urijah Faber. However, his opponent is down so his jaw isn’t vulnerable. He is delivering a hammer fist because in that position, it’s the most efficient strike.   

Now, my coach respectfully disagrees with me on this point, but I don't think physics are in your favor with chops. In my first post on size disparity, I explain that a punch gets its force from the fighter’s mass times the acceleration of the punch. The reason the mass comes into play even though it’s not the fighter’s entire body making contact is that a punch is driven by the mass of the body. With a chop you should put the weight of the body behind it but I don't think you can as much as with a punch. You don't have that same torque in the hips which really gets more of the mass of your body behind the strike.

Are knife edge chops forceful? Yes, again, they can kill a fool! And, as we all know, they can deliver enough force for a board break. I’ve broken my share of boards so I know it to be so. And, because I’ve broken as well as held board for board breaks, I know for a fact that the grain of the wood always goes with the strike, not against it. It’s true. If you do a knife edge chop, your hand will hit with the grain rather than against it. Meaning, your hand is vertical so the grain on the wood will be as well. If you hit with an sideways elbow, the grain will be horizontal like the elbow. That’s why you will see people look at a board and turn it a certain way before allowing anyone to strike it. The guy in the video goes over grain direction at about 25 seconds. 

Going with the grain makes the break easier. And, that’s ok because a board break is symbolic of strength and breaking barriers more than demonstrative of either. The one time that the grain direction of the board didn’t matter was the time I broke it with a punch. Which, I don’t suggest. It ate my knuckles up. But because the force was concentrated in a smaller diameter rather than spread over the length of my hand, foot or elbow, the grain didn’t matter.

Lastly, when you get in the cage and you see your opponent, $%&! gets REAL, real quick. You tend to go primal and just plain forget training. That's why you see even seasoned fighters do stuff they shouldn't. They're human! So, even if you are black belt chopper, that whole concept might fly right out your head once the punches start landing. As the sage Mike Tyson once said...

Thank you for that question. It was a good one and one I hadn’t really considered.  

Johne Cook: How would a knife win a gun fight?

Yes, we’ve all heard it: don’t bring a knife to a gun fight. And, it’s true…unless you are within twenty one feet of the shooter. I talked to my friend/neighbor about this one. He’s a Texas Marshal who only goes after violent offenders. The rule he and all other law enforcement officers follow is not to allow anyone with a weapon closer than twenty one feet. The reason isn’t that the criminal will be faster. But, because, in certain cases, action can be faster than reaction. 

There was a British study done that found reaction to be faster than action. However, in that study the participants knew absolutely that something was going to take place. They were simply waiting on a cue. That’s not the case with a knife wielding assailant and a police officer. The law enforcement officer has no idea what the offender may do. By the time the officer’s brain reacts to an assailant’s movement, the assailant will, in fact, be moving which makes aim with a taser or gun more difficult. If the distance between them is twenty one feet or more, the officer will, hopefully, have time to combat the movement effectively.

So, if your character has brought a knife to a gun fight, all bets aren’t off. Especially if you are Master Ken.

Thank you, Johne.

And, that’s it for this round at Until the next round, get blood on your pages.

Wednesday, October 4, 2017

Featured FightWriter, Serena Dawson - Killing a Horse & Fighting with Compromised Limbs

Serena Dawson
Over the next few weeks I'm going to concentrate on FightWriter questions. The first is from Serena Dawson.

What is a realistic way for a person on foot to kill a horse? Pole axe? Sword?

And what move/moves could a highly skilled warrior who has compromised legs use against another of equal strength and ability, (but with sound legs). The first guy had badly broken legs which healed but not that well. He can run with difficulty. 

Ok, let’s separate these out. How can a person on foot can kill a horse? 

Anything that would cause that horse to fall while in a full gallop would compromise it. What you see in the movies where the horse and rider roll forward hard, then get back up, turn around and keep fighting is incredibly unlikely. I contacted a friend of mine who is a former barrel racer. She has fallen with her horse and they were both fine. But, she said, never a hard forward roll. One like that would likely hurt the rider so badly they wouldn’t be able to control the horse. So, the horse wouldn’t be attacking you as no one would be directing it to do so. You wouldn’t need to kill it.

But, let’s say it’s a possessed horse and it’s gotta go. (We've all been there. Am I right?) First, you really have to make that horse fall and hard. Let it run at you, side step and go for the legs with a weapon. It can't just slip. It will have to make a good hard roll. Horses can get up pretty quick from a stumble, just like we can. A hard fall takes a little longer. 
Horse getting up. It's a quick moment when the legs are
all occupied and the neck is out.

As the horse is righting itself from the fall, there will be a moment or two when all of its legs are occupied and its neck is outstretched. If you have a sword, go for the neck. Even if you don't hit an artery, the strike could damage the tendons and muscles and maybe hinder it in raising its head. If it can't raise its head, its field of vision is limited. If it’s down and needs to be put out of it’s possessed misery, stab the head through the ear with a sword. (A professional told me that.)

Let's say it's not running, it's just squared off with you and being aggressive. That is an issue. You need to get a buffer between you and the horse, a tree, a rock, fencing, something. If it breached the buffer you would need to run at angles. Four footed animals aren't so good with quick turns. Unfortunately, you are are going wear out long before the horse so any weapon that helps maintain distance is going to be great. 

Watch out getting too close to the head. Horses do bite! And, avoid those back legs. Keep at a 90 degree angle with it if you can and strike at the neck.

Question two: A fighter with compromised legs would want to use the combatant’s weight and momentum against them. Tai Chi is great for that. Yes, the slow thing you see people doing is deadly. (See video) You learn Tai Chi slowly. You perform fast-ly - which should totally be a word. The only leg movement necessary would be stepping to 45 degree angles to slip the strikes. From there they would strike the ribs or the neck using "Fa Jing" which focuses all the body’s energy into a strike. It’s pretty cool.  

Hapkido would also be great as it, like Tai Chi, redirects or slips around an opponent’s momentum. It also employs joint locks that require ZERO strength. (See video) I'd also look at Wing Chun (not to be confused with Wang Chung).

Both hapkido and wing chun have ground defense techniques. And, the principles of tai chi work on the ground as well. In all of those cases, the goal is to get up which is what your character should do. They would want to get up and stay up. 

Thank you for the question, Serena. Just for you, I've attached the best horse riding scene ever. Pretty sure it's 100% real and you should use this in your M/S. Twice. At least.

Until the next round at, get blood on your pages!

Tuesday, September 19, 2017

Blades and Their Purpose Part II (And Carrying Them)

First, I want to again thank Kirk McCune for helping out
with last week's post. If you missed it, he discussed double versus single edge knives.

Ok, we are covering a lot in this post so let's just jump right into it.

There are more types of knives, blades and shapes than I have listed. But, what I have here should arm you with ample knowledge to pick or create the best blade for your character.

Types of Knives

Folder - Think folding knife. You have to fold the knife open to reveal its edge.  
Fixed - The blade is fixed in place. Kitchen knives are fixed blades.  
Gravity - A gravity knife is a knife with a blade
Balisong/Butterfly knife
contained in its handle, and which opens its blade by the force of inertia or gravity. Balisong/butterfly knives are examples. They are illegal just about every where because people cut themselves while practicing with them. Yes, really.
Switchblade/OTF - Blades are spring activated. Switchblades open like folders. Out the Front (OTF) knives reveal the blade straight out the front.  

Blade Edges

Plain vs Serrated - Plain edge blades, like the balisong pictured, are good for push cuts. Also superior when extreme control, accuracy, and clean cuts are necessary. Serrated edges grab with their points and pull to the scallops for cutting. Ideal for slicing. Even when dull, the design of the serrated blade will still cut which isn't true of the plain edge. However, the teeth will catch on clothing. It is also harder to sharpen than plain. 

Combo Edge - You can have both on a blade's edge (like the clip point pictured) or you can have a plain edge and a serrated back.

Types of Knife Blades

Clip point - One of the three most common knife blade shapes used (the others being the drop point and the spear point). The clip itself can be straight or concave and allows for quick, deep puncture and quick withdrawal. The tip can be weak though. 

Tanto - Great tactical blade. Because a good bit of metal is at the point it has great piercing ability. Also good for chopping and slicing performance.  

Trailing point - Provides a large curved cutting area. Great for slicing through. All sharp blades will slice but a curved one will slice through easier. That's why cavalry swords were curved. A straight sword would just as easily cut but would get caught. A curve allows for a good exit.    

Straight back - Because of the strong back, good for driving forward. Easy to sharpen, excellent for slicing and because of dull back, you can put your hand on it to push down.

Wharncliffe -  Great for straight, pulling cuts like box cutting.

Pen - Originally designed to cut or sharpen quills for pen. Common shape for pocket knife as it is very utilitarian. This ain’t a self defense knife.

Drop point - Because of the balance of drop points, you can change your grip and it still indexes well - meaning the blade remains at the right angle to maximize its edge. That's good because if you are using it for a tedious job or for a long time and want to move your hand around on the handle, the blade will still be efficient.

Spear point  - They can be single or double edged, although the tip is only sharp if both edges are sharpened. A spear point is for piercing.

Hawk bill - The hawk bill blade does its cutting by pulling along the material. It requires very little downward pressure to work, allowing you to simply pull with one hand. Not good at stabbing since the point faces downward. 

Sheepsfoot - Great for cutting and slicing where a point is not wanted or needed.

Needlepoint -  AKA dagger, the needlepoint is a double-edged blade used for stabbing or thrusting. It has two sharp edges which reduces the profile.

Spey - Great for skinning. It is also favored among cattlemen for castrating. Yes, really. The reason being, if the bull kicks, you won’t have a sharp point coming at you. 

Here’s two blades that are becoming more popular in movies. Thought I'd include them.

Kukri - You will hear these called knives but they are actually machetes. They're big. You won’t

find a little kukri because it's for big jobs. The shape redistributes mass, focusing it on the cutting edge near the broad tip. It is lighter near the handle. This makes the chopping motion efficient and natural. When you hold one, you just want to whack something.

Karambit - The karambit’s design provides the user with precision and stability regardless of where they are or how they are positioned: water, ice, hanging upside down. The curve allows for multiple planes of use meaning you can get all kinds of angles going. The shape of the weapon allows the wielder to "hook and destroy," as Doug Marcaida does in the video. The ring helps the user to draw quickly, maintain possession and keeps the blade from sliding back in the hand.  

Carrying A Knife

Before addressing carrying a blade, we need to address something of greater importance. If you remember nothing else from this entire post remember this: 


Never threaten with a knife. Ever. So, regardless of where the weapon is hidden, unless one is willing to kill with it, leave it be.

On that note, y'all, when carrying a knife for self defense, you have to be able to access it quickly, safely and covertly. So, when you are placing a knife on your character ask yourself if that placement allows for all three. If you have to lift a pant leg to get to the knife in your boot, that might be safe but it won't be fast or furtive. Same thing with what I call the "sexy lady" carry when women strap a knife to their thigh. Goodness, if you have to get up under a skirt, hoop and crinoline to get to the thing, that's an issue. Not to say that if I were a cowboy I wouldn't have one in my boot or if I were a sexy lady I wouldn't strap it to my thigh. But, in both cases, that would be my backup knife not my go-to.  

If it is hidden up your sleeve, you may be able to let it drop covertly, but will you be dropping handle first or blade first? If handle first then the blade may not completely drop from the sleeve and will get caught in it. If it drops blade first, well you need to be quite careful because if it drops too quickly, it could cut you. If too slowly, well, that's an issue too. Also, by the time you drop it down enough to get to the handle, the blade will be visible below the hand. So, the sleeve hide is not very safe, quick or secret.

So, where to hide it? Well, that's another post.  :) Sorry, I have to give you all a reason to keep coming back, right?

I leave you all with the best movie knife fight scenes ever. As you might imagine, they are kinda bloody and stuff. You've been warned. It starts with a balisong (butterfly knife). Watch just that little bit and you will see why people cut themselves practicing.

Until the next round at, get blood on your pages.

Tuesday, September 12, 2017

Blades and Their Purpose Part I - Single vs Double Edge

For the record, Wolverine is a single edge guy.
Last week we looked at knife vocabulary. This week, we'll look at single versus double edge knives. What is the difference and why would one choose one or the other?

First, as we saw in last week's post, a knife's edge is the sharp side of its blade. So, a double edge knife still only has one blade. Wolverine's blades are all single edge. The knives in your kitchen and any that you carry likely are as well. And, there's a reason for that. You'll see why at the end of the post.
Kirk McCune who is really too cool for me to know.

I reached out to Kirk McCune for information on this. If you don't know who Kirk is, he's a blade Jedi. He's reached the rank of Master in Giron Arnis Escrima/Bahala Na and is as knowledgable as it gets on all things stabby. I had the opportunity to talk with him once about swords and every question that I asked he not only knew the answer to but improved my question. So, he made me smarter on both ends. :) He's a kind, humble guy. You'd never know he's as lethal as he is. 

Here he is teaching in Germany. He's the guy on the left in the thumbnail.

Kirk said that like any tool, the knife is best for its intended purpose. Double edge blades, like Renaissance daggers, are excellent for fighting in close quarters against combatants in protective garments that preclude slashing. The only means of attack is a straight stab and with a double edge you cut with both the push and pull. Also, double edge is notoriously difficult to disarm because there's no safe place to grab, push or leverage on the blade. In other words, it's harder to take a double edge knife away from someone.

Renaissance Daggers
As basic tool use, Kirk has seen folks using double edge as field knives. They sharpen each side a little differently to do a different type of task: one for cutting fine work, the other for rough work like chopping logs.

The advantage of a single edge is that it allows for techniques that
place the blunt edge against your body. For example, you can conceal the knife in a reverse grip (think ice pick grip) without worrying about having an edge next to your forearm. That's not to say that you can only use reverse grip with a single edge. But if you are going to conceal it behind your forearm (which literally places the blade on the underside of your arm) it's best not to have that vulnerable part of you against something that could cut it.

In sword work, the unsharp, back side of the blade is used to block and parry which spares the sharp edge. It's also used to smash through an opponent's defenses. This makes the sword a multi-purpose tool while still sparing the edge.

Tool use for single edge allows for many camp tasks like batoning firewood where you pound the knife through your firewood with another piece of wood as a hammer. You can also place your hand on top of the knife on one side if the task calls for it.

Lastly, and this is why you likely don't have any double edges around your house, single edge knives are legal to carry in most states whereas double edges may not be. There's many opinions on why this is the case but it could be that double edges are considered weapons because of their military uses. You can own a double edge. You just can't carry it.

Some blades, like the Bowie, are "double edge-ish." They have a partially sharpened backside. This gives some qualities of both the dagger and a single edge. This sharpened swedge (that's what it's called) of the Bowie knife allows for a deadly back cut which, in Bahala Na, is known as a tip rip.

Ok, lets sum that up:
Double edge - Designed to pierce which is great when slashing isn't possible. You can cut on two sides with the push and pull. Difficult to disarm. However, there are two "live" sides to the blade which might inhibit some fighting techniques and makes utility use a bit more perilous. Illegal to carry in a whole lot of states in the U.S.

Single edge - Great for slashing and can be physically handled more safely. As such, it is has wider utility use. It can be used for stabbing but it is not as efficient as a double edge for that task. 

Double edge-ish - Best of both worlds but keep in mind that you must be mindful of where you touch the back of the blade as half of it has a sharp edge. The edge type may be legal to carry, but most states prohibits blades over a certain length. Bowies tend to be around 8" which is too long almost everywhere.

There are handling differences between the two which you should know to make your character's movements correct. Because a single edge blade only has one sharp edge, you can only slash with one side. So, in order to slash in different directions, you will have to turn your wrist over. For example, if I am attacking the neck on both sides I will have the top of my hand away from the body for both cuts. If I'm holding the knife in a reverse grip (icepick style), the turn in my arm will be more dramatic. So, in one direction, the wrist and forearm will be more vulnerable. Your character can cash in on that!
Doug Marcaida

And, finally, I'm sorry to diss on daggers, but y'all, quit just giving your character a dagger. Yes, they are easy to obscure up the sleeve of clothing (but I wouldn't) and are light, BUT they have fewer utility uses. With a single edge, you have a multi-tool that can still kill. Or, as Doug Marcaida would said, "keel." If you absolutely must, must, must give your character a dagger, I suggest they have a single edge on their person as well. Just makes sense.

Next week, I will finish up this little knife series with blade shapes, a bit on hiding your knife and why keeping a dagger up your sleeve isn't as easy as the movies make it seem. But, the Stabmaster 2200 is every bit as easy to use as this video portrays!

Until the next round at, get blood on your pages!