A battlement, i.e. a fence or breastwork, because the roofs of their houses were made flat or plain, that men might walk on them. See Jud_16:271Sa_9:252Sa_11:2Neh_8:16Mat_10:27.
Blood, i.e. the guilt of blood, by a man’s fall from the top of thy house, through thy neglect of this necessary provision.