We did a post called “Knife Fighting Do’s and Don’t’s” which you might find helpful, it’s also full of links to other resources which may be helpful.
Knife fights are dangerous, in large part because every blow is potentially fatal due to cumulative bleed out/nicking something important or even seemingly unimportant, there is no time for error much less room as combat happens remarkably quickly with the high lethality causing a sudden end, and the fight itself often happens in a blitz.
Even in the hands of someone who has no idea what they’re doing, the knife is incredibly dangerous. Just bull rushing into someone and stabbing them repeatedly in the sides or gut often as many as ten to twenty times will kill them. This is often the case in muggings, for example, and why the knife is a very popular choice. You don’t need skill in order to kill someone with a bladed weapon. You don’t even really need it to be effective beyond understanding the concepts like slashing and thrusting, swinging wildly in the heat of the moment is remarkably effective in this case.
This is the first and perhaps most important tips to writing a character who is experienced and skilled, they understand the dangers inherent in the weapon they are wielding, they recognize it, respect it, and respond accordingly. One of the problems some writers get into when trying to convey skill is to go with the approach of, “it’s not a problem for me, but it will be for you”. This is valid, the problem is that they assume the danger is nullified rather than their character’s comprehension of that danger being the deciding factor. If I know the risks involved, I can take more or navigate more easily than someone with no experience at all. However, the danger itself never goes away. No matter how skilled you are every fight can end with you lying bloody on the ground.
That’s just the way it is.
If you write a character who fights, they and you should always carry the worry of them dying in the back of their minds. And if they don’t, then you should figure out why instead of assuming it’s natural because they have “skills”.
All right, let’s dig in: Knives
Remember, two hands.
When people who have never done martial arts (and even sometimes people who have) there’s often an over focus on the weapon or on the striking, the hitting. In knife fighting and just in general, the off hand or the second hand/hand without the blade is extremely important for both defense and control. All blocking, deflecting, and the openings created will be made with the off-hand. You stop the arm with one hand, cut it with the knife. This protects you and allows you to keep fighting. The off-hand may become a sacrificial body part as necessary to lock up the enemy blade, getting the knife lodged somewhere non-vital if perhaps unpleasant is sometimes necessary to opening the path to victory.
Defense is important.
The blades will not be clashing like a swordfight (which they shouldn’t be clashing in a swordfight anyway, but that’s a different kettle). All blocks, defenses, and redirects will happen with that other hand.
Keep It Tight
Tempting as it is to use words like “swinging” or others in a similar vein, try to keep your vocabulary to descriptors that imply tight, controlled motion. You don’t want a feel that’s wild and out of control but rather intentional, directed, and focused.
“He lunged forward, swinging wildly.”
“He stepped back, off-hand catching the wrist and redirecting the incoming dagger. Slashing his blade across the back of the enemy’s hand, he dropped down. With a forward lunge, he cut up along the underside of the arm, tucked tight, and drove his weapon into their gut.”
Debilitate, Disable, Finish:
If you have the option to lunge for the kill then great, but the best way to keep your enemy from stabbing you on the way out is to get rid of their weapon first. Attacking the hand that holds the weapon on your way in ensures that you can get rid of it. The best way to avoid a double suicide is to not be so focused on killing your opponent that you forget about their weapon. The guy you just stabbed six times in the gut can still stab you before he collapses.
Prioritize your threats.
If you have the opportunity to remove the participant before the weapon then fine, but 9/10 you’re going to want to focus on ridding them of their ability to kill you on the way out before moving in.
Move, Move, Move
It can be difficult to think in multiple directions, especially if you have no experience with two bodies interacting. They aren’t going to stand there hacking at each other, they’re going to try to create openings. As any hit from the knife can be deadly due to cumulative bleed out, avoidance is the primary name of the game.
While knife fighting is fast and vicious, it’s also very much about anatomy. You get get downright surgical with a knife if you want and when writing your fiction it’s best to brush up on all the tendons, ligaments, veins, and so forth that are close to the surface and up for grabs or slashes in this case.
Medical knowledge will help you with combat in general, but with knife fighting you really want to know what can get cut to make X stop working before moving in for the kill. It sounds simple in practice, difficult in execution.
Study Actual Knife Combat/Combatants
This may seem like a no brainer, but if you really want to understand what it looks like when someone experienced handles a blade then you want to spend some time looking at guys like Michael Janich, the bladed weapons practice in Silat, Krav Maga, Marines, etc. It’s best to get that experience in person, but YouTube will also be your friend here. There are a lot different martial styles which include knives as part of their disciplines.
Take everything with a grain of salt and remember that videos online won’t make you an expert. If you’re a US citizen, you can also track down most of the Department of Defense manuals for the military available for free online. Some of the information such as that from Rex Applegate is outdated but finding his books and reading through them may help you imagine.
Half of writing anything is studying, learning what it is, what it does, learning so you can imagine the techniques in different ways. Theory for a writer is just important, if not more so than technique. You may not be able to perform it in life, but if you can grasp the theory then you can start applying that to your characters and their approaches to different situations.
Remember Violence is Problem Solving, Think of Your Character’s Personality.
Learning that all combat is not universal, that different approaches exist will help you branch out when writing your characters and allow you to develop combat styles unique to them. A good example of a narrative which does this is Season 2 of Netflix’s Daredevil, wherein Matt, Elektra, Frank Castle, and Wilson Fisk all have different approaches to using violence as a means of solving problems, where the way they fight is also an expression of who they are as people. The kinds of violence your character engages and the way they choose to utilize violence as a means of problem solving is an expression of their personality, not just their skill level.
Two characters of similar skill level can have very different fighting styles, even if they’ve studied in the same style. Take into account who these characters are and let that dictate how they choose to use violence. Not all characters are going to be efficient killing machines. Some are going to be joyous free spirits bouncing their way from one enemy to another, leaping and bounding with a blood streaked grin across their face.
You may think you know nothing, but take what you learn and then apply that knowledge to your character. Let them decide what to do with it. They might use it, they might ignore it.
Don’t sweat the small stuff.
What is most important here is figuring out how to sell the scene to your audience in a variety of different forms.