[quote=@Scarifar]
I can see one hit kills working on humans: after all, humans (and dogs) were the only physical opponents. I can't see it working on something like, say, a giant crab. Not even if he had a machine gun. 
[/quote]

Yeah, he said effectiveness varies. Obviously it won't kill a player in one hit, or any bosses. But standard enemies, I'd say one hit kill is fair, considering he dies in one or two hits. He's essentially a regular human that punches like the hulk.