You deflect attacks that could mean your ally’s death.

Prerequisites: Shield Proficiency

Benefit: Whenever an adjacent ally is the target of an attack, you can, as an immediate action, grant that adjacent ally a +2 shield bonus to AC. You must be wielding a light shield, heavy shield, or tower shield to use this feat.

Special: If you have the shield arm combar art (Or a similar ability that functions like shield arm) and the ally would have been hit if not for the shield bonus to their AC this feat provides, your shield arm takes takes lethal damage equal to the weapon's base damage, similar to blocking attacks aimed at yourself.