Being in Blessing State applies the following effects:

Recovers 50 Cost.
Increases max HP by 100%.
Nullifies status ailments.
Nullifies Unison gauge reduction effects.
Reduces cooldown time by 50%.
Recovers 20% HP every 5 seconds.
*The "increases max HP by 100%" effect is separate from other regular buff effects of the same name and cannot be removed by buff removal effects.