Ibid, we're dealing with mythology so we needn't expect ordinary experience. Being angels, they can't be killed, but they are sensitive and suffer injury. As Milton explains in Book 6:Ibid wrote: When an angel is killed do they simply spring up yet again at the back of the line? Do they go to some other heaven?
. . .Satan, being an ethereal spirit, soon heals, for spirits: "All heart they live, all head, all eye, all ear, / All intellect, all sense, and as they please, / They limb themselves, and color, shape or size / Assume, as like them best, condense or rare" (Study Master notes).