You can satisfy a somatic component using a chosen weapon.

Prerequisites: Weapon Focus, Spellcraft 1 rank

Benefit: Choose a weapon for which you have taken Weapon Focus. When casting a spell with a somatic component, you can satisfy the component of that spell as if the hand holding it were free. You cannot use this feat while grappled unless the weapon you are holding is light.

Note: Spellcasting this way does not prevent attacks of opportunity triggered by spellcasting.