You are adept at wielding larger than normal weapons in your off hand.
Prerequisite: Str 13, Two-Weapon Fighting.
Benefit: When wielding a one-handed weapon in your off hand, you take penalties for fighting with two weapons as if you were wielding a light weapon in your off hand (see Two-Weapon Fighting).
Special: A fighter may select Oversized Two-Weapon Fighting as one of his fighter bonus feats.
Source: Complete Adventurer, page 111.