Melee attacks in destiny should not have knives. Instead, they should use the players, fists and guns. Unless players have three arms, the time or would take to put away their weapon, draw their knife, stab their enemy, put the knife away, and draw their gun, would be much slow than the tube it would take to bash someone's head with the butt of your rifle. Now if you're using a knife and a one-handed gun, or no gun, that's different.