You use your weapons to hedge in your foe and trick him into exposing a weak spot, at which point you strike.

Daily   ✦     Martial, Weapon
Standard Action      Melee weapon

Requirement: You must be wielding two melee weapons.

Target: One creature

Attack: Strength vs. AC (main weapon and off-hand weapon), two attacks

Hit: 2[W] + Strength modifier damage per attack.

Miss: Half damage per attack.

Published in Player's Handbook, page(s) 106.