Improved Two Weapon Fighting

This feat gives one extra attack with an off-hand weapon. This attack is at a +5 bonus to-hit (just like your 3rd main-hand attack).

Prerequisite: Dexterity 17, Base attack bonus of +6 or higher, Two-weapon fighting.

A fighter may select this as one of his fighter bonus feats. A ranger receives this feat automatically at level 6, without needing the dexterity prerequisite.