Okay, so I hope you'll understand me somehow, since your title appears in English for me but you wrote your ideas in what I assume is Russian?
I've always loved hookswords, but I believe that such martial arts weapons should belong in another game... That's the kind of peculiar weapon that just begs to have fantastic animations, something that I don't believe would work very well in a FPS game. For a fighting game character like Kabal, it looks amazing. I guess even a TPS could showcase some incredible stuff with such weapons. But in Killing Floor? Either it would be a nightmare to animate, or they won't bother and it will look silly...
The sniper rifle idea seems like a better fit, but at the same time...Would it truly behave any differently than the Mosin Nagant? Besides having a scope, I don't really see the gun adding anything truly novel. And even picking another sniper rifle, that is not bolt-action for example... Would probably be either an under-performing M99, or a clone of the M14.