Okay, so we draw in different styles, therefore I'm not sure how well my advice would work for your lineart, however
As a rule of thumb, humans and especially drawn humans are very squishable, and the squish goes a long way to add impact/force to something.
Pardon a very rough sketch, I didn't opt for an actual lineart since, again, different styles.
I personally use "the squish" in fight scenes a lot:
On a very very quick edited quess in your style it could look something like this (and regardless of line weight, I think a couple of facial expression wrinkles coult possibly help with the intensity of expressions, which, in turn, also could add to the impactfullness. Like so:)
This is how I'd personally approach it within the bounds of your style, anyway. You're, of course, free to make what you wish of this advice, we're all constantly learning ^^