User blog comment:B214/Question and Answers 4/@comment-120.20.128.230-20141007071346/@comment-24098614-20141009211904

Devils make it quite clear that a Human that doesn't have a Sacred Gear is useless to them as Peerage members because they don't reincarnate Humans out of the generosity of their heart because Rias did reincarnate Issei but if Issei was a normal Human with no Sacred Gear she wouldn't have bothered with it because she might have a kind and compassionate heart but like any Devil she has common sense not to waste a Evil Piece on someone that doesn't have nothing to offer to her.