This is the second best of your scraps, and with a few changes could in a new version could easily be good enough for the main gallery: first off, her knife seems odd--I'm not sure what it is, but it looks like she's not holding it fully. I'd say try adding the top of the handle/end of the hand sticking out of the top of her hand a bit, and redraw the blade so that it's flowing with the direction of the handle (it seems like its fixed onto the blade to the left to much, when it should be angling to the right a little more. Look at the handle/guard/blade connections for a second, imagine it being a real knife you bought at a store, and you'll see what I mean.) Her right leg also needs more muscle breaks/bendy to it, it looks too straight even for that pose.

Again, this is excellent posing, and the way you fill up white paper is excellent. Most would just have her standing normally, with maybe a glare in her eyes and the knife just at her side or holding it up with a "Wow, look at this!" look, but no, you dared to bother drawing an action pose. I think if you made those changes I mentioned and colored her, it would do wonders, especially if you emphasized how deadly calm she is (it's a great change from the grinning characters or glaring ones you usually see, and can tell a lot about the character: she's either crazy, used to too much violence, or very good at what she does--or all three!)

Also, maybe draw a background. Something actiony, and make her standing on something, or else she looks like she's floating in mid-air. Maybe a ton of guys standing around her with weapons, or a bullet streaking by her to hit a wall behind her. Something like that.