When using a mace it does very minimal damage. For example, using a stone mace head plus 2 sticks it makes a mace that states it does 10.5 attack damage (or about 5.25 hearts of damage). Upon using this mace on a cow with 5 hearts it would normally die from that damage. Instead, it does 4 attack damage (or about 2 hearts) and it won't injure entities that are outside of dagger range. I feel it may have had it's stats changed to that of a dagger behind the scenes here.

Yeah, the damage scales as armor increases.

The range thing sounds like a bug, but the damage is working properly. Maces only do full damage against armored foes.

Hm. I was having difficulty testing that. Tried on an iron golem and noticed no difference. Is it more damage with more armor?

Fixed the shorter range and completely changed how maces work in a recent update, so they should now do the amount of damage shown in their tooltip.