The Silver Shield
In 'Harry Potter and the Order of the Phoenix', during the fight between Voldemort en Dumbledore, Voldemort summons a silver shield which protected him from a curse of Dumbledore. Since the curse was powerful enough to blow through Harry's hair, even when he was standing behind the golden statue of the Centaur, and the shield could repell it, we are sure that the silver shield was seemingly powerful.