The mace's sounds make the neutral (Friendly Creatures) sound category instead of the Players sound category. This is inconsistent with other weapons like the sword, which use the Player sound category for attacking sounds.

To reproduce

Change all sound categories except for Friendly Creatures and Master to 0%. Summon a pig and a bee. Smash each from a height of at least 1.5 blocks, and notice that the mace sounds appear.

Code analysis

In net\minecraft\world\item\MaceItem.java, in hurtEnemy, the sound events are called with the SoundSource.NEUTRAL sound category.