See also: Feats
You are particularly skilled in using a particular type of weapon.
Effect: Choose a single Exotic Weapon or weapon group, you gain a +1 bonus on all attack rolls you make using the selected Exotic Weapon or weapon group.
Special: You can gain this Feat multiple times. It's effects do not stack. Each time you take the Feat, it applies to a new Exotic Weapon or weapon group (Including Unarmed attacks). If you take this Feat with Heavy Weapons, it works normally with Vehicle Weapons.
Additional Weapon Focus Effects
Combined Feat (Weapon Finesse): When you are wielding a single one-handed weapon for which you have Weapon Focus, you can treat that weapon as a Light Weapon.