You have focused your training on weapons of a particular type.
Prerequisites
Proficiency with selected weapon group, base attack bonus +1.
Benefit
Choose one weapon group (or weapon-like ability). You gain a +1 bonus on all attack and damage rolls you make using weapons from the selected weapon group.
Special
You can gain this feat multiple times. Its effects do not stack. Each time you take the feat, it applies to a new weapon group. A spellcaster can select “ray” as a weapon for Weapon Focus. Some abilities may grant Weapon Focus for one or more specific weapons. In such a case, you do not gain the benefits of this feat for other weapons in that weapon group.