Shields don't block mace smash attacks

When blocking with a shield, a mace smash attack bypasses it entirely.

Steps to reproduce:

1. equip a shield and block with it
2. have someone else hit you with mace smash attacks while still blocking with your shield.

Expected result:

The shield blocks all damage from the mace smash attack.

Observed result: 

The mace smash attack ignores the shield and damage goes through.