Blessings, curses and poisoning could be new temporary effects.
Blessings could be bought and would increase your stats (+20 def or +100 HP or so) for a certain number of fights.
When fighting some monsters there would be a chance that you get cursed or poisoned. A curse would lower your stats and you would have to pay to have it lifted (of wait a fights). If you get poisoned you would lose health over time. There could be an antidote poison or an extra fee at the healer to get rid of it.
Maybe there could also be items/weapons/skills with a curse or poisoning effect so you could poison the monster or lower its stats.
there's already poisoning in game! with the respective cure or at least there was, but as I see it it doesn't cause much of a dent to even go and apply the cure! either that or my poison immunities leaked onto my characters