Crescent Moon

 
Prerequisite(s): Improved Disarm, Improved Two Weapon Fighting, Two Weapon Fighting, Weapon Focus (Dagger and Bastard Sword, Longsword, Scimitar or Short Sword)
 
Benefit: If you hit the same creature with both your sword and your dagger in the same round, you may make an immediate disarm attempt as a free action.
 
Source: Complete Warrior