High Sword Low Axe

 
Prerequisite(s): Improved Trip, Two Weapon Fighting, Weapon Focus (Bastard sword, Longsword, Scimitar or Shortsword and Battle Axe, Handaxe or Dwarven Waraxe
 
Benefit: If you hit the same creature with both your sword and your axe in the same round, you may make a free trip attempt against that foe. (If you succeed, you may immediately use your Improved Trip feat to gain an additional attack against your foe.)
 
Source: Complete Warrior