Greater Weapon Specialization [General]
Choose one type of weapon for which you have already selected Weapon Specialization. You can also choose unarmed strike or grapple as your weapon for purposes of this feat.
Prerequisites: Proficiency with selected weapon, Greater Weapon Focus with selected weapon, Weapon Focus with selected weapon, Weapon Specialization with selected weapon, fighter level 12th.
Benefit: You gain a +2 bonus on all damage rolls you make using the selected weapon. This bonus stacks with other bonuses on damage rolls, including the one from Weapon Specialization (see below).
Special: You can gain Greater Weapon Specialization multiple times. Its effects do not stack. Each time you take the feat, it applies to a new type of weapon.
A fighter may select Greater Weapon Specialization as one of his fighter bonus feats.
Source: SRD 3.5 Feats