How would Red Mage fit in this game?

[MetalheroD]

With a weapon like a rapier or whatever, I don't see RDM as a tank aesthetic-wise. Wearing heavy armor with a rapier as a weapon seems impractical, let alone using a rapier to tank.
But with it's capabilities, It fits being a tank. Though, I prefer it being something else.
Blue Mage seems better as a tank, because of the concept.

Why are you assuming that a tank HAS to wear heavy armor?
Also, BLU's "concept" is that they use monster's ability. They have no more concrete claim to being more "Tanky" than RDM does, and RDM has the added advantage of already being in a trinity with a healer and a DD, meaning a tank is all that's missing.