Do YOU think we'll get a new Tank and/or Healer in 4.0? And vice versa.

[Fevelle]

It's called magic, more specifically Phalanx. They can also have parry traits with their fencing style swords that minimizes actual damage taken.

Red Mage is not a fencer, he's a caster. The way RDM tanked in FFXI was by adding Mystic Knight traits and skills to it, completely crushing the RDM personality.