Prerequisites: Dex 17, Two-Weapon Fighting, base attack bonus +6.
Benefit: In addition to the standard single extra attack you get with an off-hand weapon, you get a second attack with it, albeit at a -5 penalty. See the Two-Weapon Fighting special attack.
Normal: Without this feat, you can only get a single extra attack with an off-hand weapon.
Special: A fighter may select Improved Two-Weapon Fighting as one of his fighter bonus feats.
Unlocks: Greater Two-Weapon Fighting (1/2)