You may fight with a one-handed weapon in your offhand as if it were a light weapon. In addition, you may use your [Strength] score instead of your [Dexterity] score for the purpose of qualifying for [Two-Weapon Fighting] and any feats with Two-Weapon Fighting as a prerequisite.
That last bit makes it clear that Two Weapon Defense should qualify. I know you're not really working on the game atm but this would be a nice fix.
You may fight with a one-handed weapon in your offhand as if it were a light weapon. In addition, you may use your [Strength] score instead of your [Dexterity] score for the purpose of qualifying for [Two-Weapon Fighting] and any feats with Two-Weapon Fighting as a prerequisite.
That last bit makes it clear that Two Weapon Defense should qualify. I know you're not really working on the game atm but this would be a nice fix.