We actually already have one of the Lucavi.

You might remember Queklain (the very first one you fight--the Cardinal, whose name I can't remember). Queklain is a poor transliteration of Cuchulainn (which was corrected in the War of the Lions translation), who we find wiping nine out of ten alliances in the Void Ark. I believe he's showed up in other FF titles as well (FF6 maybe—I only played that one once).

But I can't lie, the first thing I thought of when I saw Yoshi's screenshot was Belias/Velius from FFT, too.