Yeah they added on En-spells to RDM in XI, but you have to admit it fits the job, sword wielding magic user, why wouldn't they buff their weapon with magic? The problem with Mystic Knight is that it only does the one thing, it's not rounded out enough for a MMO job, in XI they gave it abilities that RDM already had (bar-spells and phalanx and some other enhancing magic) in order to round it out. As far as I'm concerned Rune Fencer was only made to appease RDM melee pushers without having to change RDM at all, but all they did was piss them off.

But that was XI and this is XIV, the two jobs certainly are similar and I wouldn't mind them both stemming from a single class, with RDM being more support focused and Mystic Knight being tank focused.