Me think they be the old boys that were sacrificed by Naaru, you know, the ones that this chatterbox of a bitch blade spoke about. It does make sense. It also makes sense that Void touched Ethereals would hold a grudge against the Legion. Sarguhrer destroyed the world where Nathrezim lads were slurping them thick tentacles. Maybe it as not machinery after all that made them spookies, but mighty bite from purple guys.