Improved Multiweapon Fighting( Deities and Demigods, p. 51)
A deity with three or more hands can fight with a weapon in each hand. The deity can make up to two attacks per round with each extra weapon.
Multiweapon Fighting (MM) , DEX 15, base attack bonus +9, Multidexterity, three or more hands,
Greater Multiweapon Fighting (DD) ,
In addition to the single extra attack the deity gets with each extra weapon from Multiweapon Fighting, it gets a second attack with each extra weapon, albeit at a -5 penalty.
This feat replaces the Improved Two-Weapon Fighting feat for deities with more than two arms.
With only Multiweapon Fighting, a deity can only get a single extra attack with each extra weapon.