Strength of a Warrior (3.5e Feat)
From D&D Wiki
Strength of a Warrior [General],[Fighter]
Your muscle bound body while not taking damage with any less pain or suffering, does tend to try to avoid it more often, relying on your ability to take attacks head on as well as rolling with them.
Prerequisite: Base Attack Bonus +5, Strength OR Constitution 17+
Benefit: You add to either your Strength or Constitution modifier (Highest of the two) to your armor class. Your Newly added modifier doesn't take place of the armor Dex Modifier.
Special:The AC bonus gain from this feat are retained even when flat-footed. This feat can be taken twice, first time adding one of the bonuses, either Strength or Consitution, then adding the other one.