In FFXIV many people are still very narrow minded thinking that RDM will be primarily a magic class. As we all know, weapons of choice in FFXIV determines your job. And can we all guess what is RDM's weapon of choice?? If you said SWORD & SHIELD you were spot on!! Having that said I believe RDM can be branched from the Gladiators (GLD).
Gladiators abilities are all made for a tank class and thats exactly what I think RDM should be. What could make RDM a great tank is its magical prowess!! I RDM learns a variety of buffs spell including the magnificent Phalanx!! A spell that raises defense sharply. So if we add the sword moves from the GLD ability set and 5 more moves (mainly magicks) as Job specific abilities for RDM we have an very good operating mage tank and RDM can still keep its title of "Jack of all trades"