Shield Brace (Combat, Shield Mastery)Source Armor Master's Handbook pg. 19
You’ve mastered the art of balancing a polearm’s weight against a shield’s stability.
Prerequisites: Shield Focus; base attack bonus +3 or fighter level 1st; proficiency with light shields, heavy shields, or tower shields.
Benefit: You can use a two-handed weapon sized appropriately for you from the polearm or spears weapon group while also using a light, heavy, or tower shield with which you are proficient. The shield’s armor check penalty (if any) applies to attacks made with the weapon.Source Armor Master's Handbook pg. 21 (Amazon)
You can spend 1 stamina point to negate the penalty on attacks for using this feat for a single round. (See page 19.)