Eraqus has always rejected the darkness so I don't see how it would work with him becoming an nobody. He isn't from an special birth like the select few that have a connection to Sora. And he never got killed by a heartless or even the negative energies of an inverse (if that was ever thrown into a loop hole). If Eraqus was MF I don't see why he would want to test his apprentices like that. It makes no sense. MX wouldn't need Eraqus to accomplish his goal now that he has Terra. Those blades seem more like Xehanort and Xenmas related to me.