This mod will not be updated past 1.21.3 since this can now be implemented with resource packs.

For versions above 1.21.3 check https://modrinth.com/resourcepack/mace-but-3d-resourcepack

Mace but 3D

Many players including myself were disappointed when they found out the mace wasn't going to have a 3D model in 1.21. Well this mod fixes that.
Mace but 3D is a fabric mod that adds a clean 3D model to the mace. Unlike in resource-packs, the custom model appears only while holding it, giving it a more vanilla feel.

For example, while in an item frame, the mace retains its normal model like the trident and the spyglass.

The mod is client-side and should work perfectly in any server.
You are free to put it inside your modpack.