I have an idea for a caster/tank.

[Xlantaa]

Well. It is important their equipment too. As tank they will be strictly attached to Fending gear (heavy armor) and STR/VIT base stats, independent of the skills they have. So the idea of a light armor/cloth tank will not be possible with the current itemization of Final Fantasy XIV. The weapon can be anything, because is unique per job, but the armor is strictly in this line. A caster tank, if you choose to change his base stats to INT, will cause either need use caster gear or have is own exclusive gear, and neither of them will happen unless they heavily change the game core.

Of course it is still possible a caster tank, but the equipment will be shared with the other tanks.