I was talking about AoD, not about any enemy. AoD cannot open doors so it's possible to kill him without weapons and Berserking.
This tactic is nearly useless on later levels, because most of monsters there fires missiles, or can open doors. But here is list of enemies that can be killed this way without having damage: former human, former captain, former commando, demon, lost soul, Angel of Death, Arachnotron, Pain Elemental. Imho ability to kill all this enemies without damage to yourself is not so useless.