Prerequisites: Dex 15, three or more arms, Multiweapon Fighting, base attack bonus +9.
Benefit: In addition to the single extra attack a creature gets with each extra weapon from Multiweapon Fighting, it gets a second attack with each extra weapon, albeit at a –5 penalty.
Normal: With only Multiweapon Fighting, a creature can only get a single attack with each extra weapon.
Special: This feat replaces the Improved Two-Weapon Fighting feat for creatures with more than two arms. A ranger who meets only the base attack bonus prerequisite and the Multiweapon Fighting prerequisite can gain this feat, but can only use it when wearing light armor or no armor. A fighter can select Improved Multiweapon Fighting as one of his fighter bonus feats.
Source: Standard Reference Document under Open Game License v1.0a, which updated this feat originally published in the Epic Level Handbook, page 70.