So I played on the demo today and these are the bugs I discovered:
I spawned in once and had no hud, couldn't type in chat and was the gray freeman model, fixed when I typed retry in console.
Knife attack speed might be the reason its animation doesn't play when attacking a player or surface.
You should use SWEP.HoldType = "knife"
Maybe move the pistols to slot 2? Also I'm not sure why you spawn with 2
Hitting a zombie with a melee while they are jumping sends them flying, not sure if intended or not