User blog comment:Mnzombie/Issei's Peerage/@comment-68.203.220.111-20130508224945/@comment-68.203.220.111-20130508225928

Oh yea I forgot to mention Sona mentioned in volume 14 that her original choice for Knight didn't pan out so she went with a backup which is Bennia, I think this unnamed Knight might be the one that takes the second Knight slot in Issei's Peerage.