You can tell I’ve been stuck on shields for the last bit. Not sure why, but I have been. Let’s keep going with a Pathfinder feat for Shields.
Shield Bash Assault (Combat)
You shield is a deadly weapon in your hands.
Prerequisite: Shield Proficiency
Benefit: When you perform a shield bash, increase the damage dealt by the shield by one die. As an example a d6 damage would becomes a d8 damage. If something modifies the shields damage like enchantment bonuses or changing damage type, this feat still applies.