we need Riot to expand the Valkaryie/Dark Valkaryie skins line

So why not give the rifts' own angelic sisters one each (your choice who gets which). You could also give Riven one (just make sure the wings are broken...), and one could go to Fiora (maybe as the opposite of Riven?).

Hmm, there really is a lack of sword-wielding women in this game....