The spirit stat doesn't feature all too much in this game. Does this mean that cure is boosted by the MAG stat and not the SPR stat?
You can boost the faith stat using Fina's "Cheer" ability. Currently the only way to boost faith. To reliably do it, her Cheer ability should be at least level 11. Fastest way is have your own as well as hire a companion Fina and have them use all 3 of their charges on whoever you're trying to raise the faith of, for up to a total of 6 per battle.
Oh damn, I've been using Macherié as the unit in my guild and her faith has dropped to 30. Is there a way of boosting the faith stat?
Curerntly it's suspected that the amount of HP refilled by Cure refers to the caster's Faith, MAG, Level of the ability, and target's Faith.