Ogrork the Mighty
Explorer
The Invisible Blade prestige class (Complete Warrior) has an Unfettered Defense ability that allows you to add your Int bonus to AC (unnamed) so long as you are not wearing armor and are armed only with daggers.
The Duelist prestige class (DMG) has the Canny Defense ability (below) that seems to do the same thing.
Canny Defense (Ex): When not wearing armor or using a shield, a duelist adds 1 point of Intelligence bonus (if any) per duelist class level to her Dexterity bonus to modify Armor Class while wielding a melee weapon. If a duelist is caught flat-footed or otherwise denied her Dexterity bonus, she also loses this bonus.
The question is, do they stack?
The Duelist prestige class (DMG) has the Canny Defense ability (below) that seems to do the same thing.
Canny Defense (Ex): When not wearing armor or using a shield, a duelist adds 1 point of Intelligence bonus (if any) per duelist class level to her Dexterity bonus to modify Armor Class while wielding a melee weapon. If a duelist is caught flat-footed or otherwise denied her Dexterity bonus, she also loses this bonus.
The question is, do they stack?