A talent for Cha-based rogues, that scales with level and stops you getting pounded into the floor.
When you are aware of a melee attack on you and not flat-footed, you may, as an immediate action, use a Bluff roll instead of your AC against that attack. You cannot use this ability more than once against a given opponent.
For example at 1st level, a Cha-based rogue (Cha 16, Dex 12) might be AC 14 (leather) and have Bluff +7, for an effective AC of 17.5. At 8th level, he'd be AC 22 or so, and have Bluff of about +19 = AC 30. At 15th level, Bluff might be +35 with 4 uses of Honeyed Words to become effectively AC50, once per opponent.
Could be a feat, but then Bards and Sorcerers would eat the rogue's lunch again.
[edit: swift -> immediate]
Not bad. Reminds me of Snake Style.