Bonded Weapon

 
Prerequisite(s): Base Attack Bonus 8+, Proficient with Weapon, Improved Critical (with weapon), Weapon Focus (with weapon), Weapon Specialization (with weapon)
 
Benefit: Choose a single unique weapon. For one month you train exclusively with that weapon, learning how to best wield that specific weapon most effectively. During the training period, you may use no other weapons or you must repeat the process. After the month of training, give the weapon a name to symbolize your intimate knowledge of the weapon. You gain an additional +2 to all attack rolls and +1 to damage with your named weapon (this stacks with the weapon focus and weapon specialization bonuses). You do not gain the bonuses or penalties of this feat when wielding a weapon of the same type, and suffer a -2 to all attack rolls with all other weapons.
 
Special: If ever your named weapon is destroyed or taken from your possession for more than a week, you must repeat the process of naming a weapon and continue to suffer the -2 to attack rolls with all weapons of a different type. You may never have more than one bonded weapon.
 
Source: Mongoose Ultimate Feats