Natural Defenses: guard and toughness +1, costs 2.
Two Weapon Defense: if you wield two weapons with attack specialization, guard +1. Costs also 2.
Is the purpose of two weapon defense, that you take it on top of natural defenses? Because otherwise it is strictly dominated. Maybe the cost should be reduced to 1?
The rational was that Natural Defense doesn’t stack with armour, while Two Weapon Defense does, so while Two Weapon Defense is weaker you can compensate that fact with wearing armour.
If you are the GM and you still feel that Two Weapon Defense is too weak, than feel free to reduce the cost to 1 feat. I don’t think it will impact balance that much, so I don’t see much harm in that.
Ahh, I missed that natural is only without armor. Thanks for the answer!