Draco looked around at present company, which included Harry, holding his wand as if it was a bomb about to explode, two of the older aurors, and one of the ship supervisors who had taken over for Bagnell in the task of scraping burnt pieces of Karathen from the ship. In a tone that suggested this was Unspeakable knowledge, Draco articulated (in a rather condescending voice) that copper; the generic, conductive, run-of-the-mill element, can make magic impossible to perform. The exact words were "We’ve been working with Azkaban to decrease incidents of wandless magic, and copper-plated cuffs are currently in testing phases, as from our research, copper in high purity can block the ability to do magic, entirely"