BLU can be a full job. Here's how:

[ChaseNetwork]

The potential party imbalance from BLU is primarily due to having skills that can essentially negate the need of a dedicated tank job and white wind IMO being fairly OP as a healing spell. At end game item levels we'd be looking at an AoE heal potentially doing about 35K+ HP per person.

Gameplay wise yeah most status effects are only going to be usable on trash. IMO rather than changing cooldowns I would rather add a bit more depth to gameplay by reviving the element rotation previously used by ninja in FFXI for their ninjutsu spells to be an ever rotating chain based on spell element to either gain potency or a bonus. So the specific spell doesn't matter just the element affinity of it would.

In the end however given how BLU is currently I wouldn't want it queueable in standard DF or roulettes without a premade party. I wouldn't mind it being usable in diadem, eureka, solo duties from quests and MSQ, and squadron missions.

Suppose Chaos dropped everyone to 1 HP at the start of the Dark Crystal phase, and you only had BLUs for healing... how would that work?