Live by the sword implies the use of the tool, not merely the existence of the tool. This man didn't murder anyone, it wouldn't be divine comeuppance for him to die. It would make as much sense (i.e. none at all) to look at a demolition engineer and say, "He worked with explosives, a bomb-maker, it's fitting that it exploded in his face." This man has not "lived by the sword" by any sane definition.