Here are some suggestions to make S&B better.
Improved Shield Bash - Gives the wielder the ability to two-weapon fight with shields, with the shield treated as an off-hand weapon. The shield is treated as a light weapon when used in this manner.
Coupled with improved shield bash:
Green Steel Shields - +5 Green Steel Shield, +2 Reinforced Plating, treated as a weapon for purposes of crafting, 1d10 base damage + 1/2 strength bonus + other modifiers
Normal Shields - 1d8 base damage + 1/2 strength bonus + other modifiers, possibly add weapon effects to randomly generated shields since it is rare that ones are used with other modifiers.
And for defense:
Shield Mastery - grants a 20% chance for the wielder to block incoming attacks without utilizing active block, grants the same bonuses to DR from blocking as normal, but not the +2 AC.
Improved Shield Mastery - grants a 35% chance for the wielder to block incoming attacks without utilizing active block (does not stack with Shield Mastery), grants the same bonuses to DR from blocking as normal (stacks with the similar Shield Mastery effect) but not the +2 AC.