I've never heard of such a feat, but I think the idea is a great one! I've been looking for some sort of limiting mechanic on the "Trde in AC for Damage" equation, and Dex mod might just be it. A little low for some, but there's little reason to take the feat if you can't really benefit from it. I could see it working like Power Attack or Combat Expertise (and perhapse, like Combat Reflexes, Dex mod + 1 would make more sense...) When combined with Combat Expertise you have a weak man's Power Attack, limited to 5 points. Really great idea, I like it muchly. Consiter your concept stolen.
Now, if I can only pass it past my GM...
What would the Prereq's be?
- Kemrain the AC Twink.