Mace currently can be enchanted with Mending and Curse of Vanishing. However Java Edition 24w13a also allows mace to be enchanted with Unbreaking, Smite, Bane of Arthropods and Fire Aspect.

These existing enchantments can now be applied to the Mace:

Mending
Unbreaking
Smite
Bane of Arthropods
Fire Aspect
Curse of Vanishing

Steps to Reproduce:

1. Enable the "Update 1.21" experiment.
2. Obtain a mace, and an enchanted book of Unbreaking, Smite, Bane of Arthropods and Fire Aspect.
3. Try to combine them in an anvil.

Observed Results:
Mace cannot be enchanted with Unbreaking, Smite, Bane of Arthropods and Fire Aspect.

Expected Results:
Mace should be able to be enchanted with Unbreaking, Smite, Bane of Arthropods and Fire Aspect.