The idle, is good, but the fingers on the left hand need to have a more noticeable bend in the middle and tips of the fingers. Right now it looks like you just used the bottom of the fingers. Try looking at L4D's zombie hand idle, the fingers curve a lot, but still in the human capabilities. I think the finger movements would fit great in this.

The first melee, really isn't a way I'd swing a knife. And even if it was, it wouldn't exactly stop right at the edge of the screen. I'd either go with a melee that comes from the left and swings across to the right, sort of like some backhand tennis swing, or change the position of the hand so that it's facing down during what you have now. Whichever one you want though, I think my second option would look cooler though. I'm going to skip the second melee because I really haven't used a knife so I have no idea if that's logical or not.

Something I always love doing though is something I abbreviate to r2o, or Return 2 Origin. Right now, yours look a bit strange, or too stiff like during the ready. Add some interesting movements, instead of just placing the origin's frame after you're done with the main part of the animation, because then the rotations get really effed up. You'll soon start doing it, I used to just place the origin's frame, then when it was halfway there, raise it up a bit. Here, try rotating it a bit in the opposite direction it's going as well as moving it up a bit, or down if you want to try something with that.

Dear lord, I've typed way too much. I only have limited use of an ICEE Crit, and I'm way over. Now I've got to pay him a bunch of money
Also, was that quick crit? Sorry if I went overboard, first time actually posting my opinions in here. Don't kill me.