You are only now coming into the places where mob damage starts to ramp up good.
Sure, a shield may block only 2 or 3 strikes per fight, but when those strikes are for 500's, your Healer will be thanking you.
You are a Guardian. It is not your job (or mine) to kill the mob. Thats for the fancy schmancy DPS people to take care of. We're just here to [Removed for Content] the mob off.