[2019] Why doesn't the mace one shot no helmet?

I'm legitimately curious. Realistically it could. So lets talk about Balance instead. Who wears no helmet? Idiots. Idiots or Archers. Neither are usually very good, and if you want to one shot no helmet users, it's not like there are cheaper and faster alternatives (The Falchion or Cleaver for instance) Hell, the Heavy Handaxe, while slow still one shots level 1 helmets as well.

I don't get it. It doesn't need any change in damage to anything else. I just don't get why it doesn't one shot no helmets.