Might be a stupid question, but do you need to hit when using Shield Material Expertise and a Darkwood shield?
Benefit(s): When wielding a shield made of one of the materials listed below, you can use the listed ability twice per day.
Darkwood: As a free action as part of an attack with your shield, you can drive splinters of your shield into your opponent, dealing an amount of bleed damage equal to 1 + the shield’s enhancement bonus.
When you make an attack with a shield, you can take a free action and deal bleed damage to your opponent. It doesn't mention a need to hit, but auto-damage sounds a bit ... unusual, so I might at well ask.
Since it says "as part of an attack with your shield", I believe the attack would have to hit in order for you to do the damage.