The bug
Mace do not working on mobs.
Steps to reproduce
Build a 5-7 blocks pillar
Summoning a piglin with mace. (Why I don't use zombie to test, because MC-184885)
/summon minecraft:piglin ~ ~ ~ {HandItems:[{Count:1,id:mace},{}]}
Surrounding self
Let the piglin attacking you.
You won't get more damage.
Please attach steps to reproduce this issue, as well as observed and expected results.