Needs review
Source: Player's Handbook

Description: You are a master at fighting two-handed.

Prerequisites: DEX 19, Base Attack Bonus +11, Two-Weapon Fighting, Improved Two-Weapon Fighting

You get a third attack with your off-hand weapon, albeit at a -10 penalty.

Special

A fighter may select Greater Two-Weapon Fighting as one of his fighter bonus feats. An 11th-level ranger who has chosen the two-weapon combat style is treated as having Greater Two-Weapon Fighting, even if he does not have the prerequisites for it, but only when he is wearing light or no armor.