Test your Creativity: Mage Tank

In almost all MMO's Tanks are plate wearing beings generating aggro with taunts and physical attacks, WoW did smething slightly different with their Druid (shapeshifter) but in essence, it was the same basic setup. Endure the full brunt of the damage and load up on as much armor as you can. What I'm suggesting here is something different and want your ideas on how YOU would make it work in FFXIV, The mage tank.

Mage style HP pool and armor, utilizes shields to block incoming damage (reducing say 100 points of incoming damage to 10 points damage actually received) instead of merely enduring said hits

Shields reflect damage based in INT and generate aggo and drain MP (tank stance) shields absorb damage and regenerate mana accordingly (either using INT or MND) but doesn't generate aggro (Rest/dps stance)

How would you make it work? what you you change/add?