I think they'll just fuse it with Mystic Knight/Spell Fencer as a DPS and call it a day. It'll wind up maybe a little like NIN, BLM, and SMN in various ways, doing melee combos and a few spells, enchanting its weapon (astral/umbral/3rd element like mechanic) so it gets by with INT main stat and no stancing, and offers a lot of utility from healing/raise to single target resource recovery to vulnerability inflictions and other debuffs.
