I don't know if it's been mentioned before; if it had I'll give you this:
It's a bug that I'm having with the knife really rarely (even though I mostly play with knife);
I think it's when I drop my gun to pick a knife from the ground, then the player automatically throws it as well with a speed that can't really be reached with a normal throw.
I've been trying to do it intentionally just to take some advantage of it but I failed. Maybe someone can explain how it works or why isn't it getting fixed?