Girallon's Blessing

[Raging Gene Ray]

What about using the extra arms to cast spells?

For example, a spellcaster polymorphed into a hydra with two little arms to execute the somatic components for spells?

Also, you can either make claw attacks OR attack with a weapon. I'd rule that if you're holding a weapon, you can't use that claw to attack.

So a 4 armed Fighter holding a sword in 1 would have to choose between 1 sword attack or 3 claw attacks.

I think that's how the Spell Compendium words it...nothing about not using a shield though (although you might have to choose between the shield and using that arm to make a claw attack).