The new combat changes have got me thinking about a way to make S&B worthwhile, and I've come up with this, feedback would be greatly appreciated:
Add Shield Bash as a proc similar to offhand attacks and add Passive DR whilst wielding a shield (to simulate hits grazing off the shield even when not actively blocking)
Non-proficient 0% proc.
Proficient +10% Passive DR 1/- (Tower Shield proficiency gives DR 4/-)
Then add the following to the shield related feats, on top of existing bonuses:
Shield Mastery - +10% proc rate, Passive DR 3/-
Improved Shield Mastery - + 10% proc rate, Passive DR 5/-
Improved Shield Bash - +20% proc rate, 2d6 additional bludgeoning damage.
All bonuses would be stacking, so a fully specced shield user would have:
DR 9/- (DR 12/- if Tower Shield) and 50% Shield Bash proc at +2d6 damage.
Numbers ofcourse could be adjusted for balance. The idea is it brings it a little closer to THF and TWF in terms of damage, but retains the defense over offense balance that it should have.
On top of this add more possible stats to shields, those which affect both hands when on one weapon for a TWFer, like Seeker, Backstabbing etc.