I was going to rant but decided to just make my point instead.

Not every Pld has an Aegis. It's highly possible that the purpose of this job is to fill the role of "the tank for magic using targets", for small groups and such. We'll have to see what they share with us, when they finally give us a bit more details (like they did for Geo). But just like Pld was used for tanking certain types of enemies (back in the day), Rnf could be the same thing, just for the other side of the damage types.