Potter pulls out Draco’s hawthorn wand from his pocket and admires it before handing it over. He introduces him to the Deathly Hallows and the Elder wand, that for a couple of months Draco was the master of the most powerful wand known to wizardkind and he didn’t even know it—no, he’s not bitter at all,  not at all—and by disarming him in Grimmauld Place the wand transferred its allegiance to Potter.