Harry's reaction was so fast Hermione would later tell him she didn't see it as anything more than a blur. He flicked a Severing Curse at the Constable, which sliced his wand arm clean off at the shoulder. He screeched in agony and collapsed into the pool of blood which spilled out from the wound. But, before he had even hit the floor, Harry had transfigured his lost wand into a dagger and driven it through his skull. It caused his eye to pop out of its socket as the blade cut through the optic nerve.