SRD:Perfect Two-Weapon Fighting
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Perfect Two-Weapon Fighting [Epic]
The character can make as many attacks with his or her off-hand weapon as with his or her primary weapon, using the same base attack bonus. The character still takes the normal penalties for fighting with two weapons.
Without this feat, a character can only get a single attack with an off-hand weapon (or two attacks with an off-hand weapon if he or she has Improved Two-Weapon Fighting, or three attacks with an off-hand weapon if he or she has Greater Two-Weapon Fighting).