Just give BLU a mace and a rune shield and call it a day. MNK's now have a tank that they can share blunt debuff with and PLD no longer has the monopoly on blocking. Plus it's very symmetrical having two tanks with 2h weapons and two tanks with a 1h and shield set up. They could even push it further and make WAR and DRK more offensive tanks and PLD/BLU more party/support tanks.

They also need to give tanks a cross class skill akin to trick attack. Tired of seeing a nin in every party and would like to see some variety.