Call of Duty: Black Ops
If the player fails to pick up the Tomahawk at the beginning and alerts the enemy, the player will be able to punch by pressing the melee button. The melee sound will be that of a knife, and the punch will kill the enemy in one hit. It is not recommended to try to use this in the mission, as all of the personnel in the area, including the helicopter, will attack the player (unless the player has the "godmode" command enabled).
The "weapon" is also seen in the mission "Revelations" although the player can't attack with it.