Out of the Abyss
Piety (pahy-i-tee) Devout fulfillment of religious obligations.
As you may or may not know, the gods of the Forgotten Realms take an active stake in the lives of mortals. Mortals who pledge themselves wholeheartedly and live according to the dogma of their deity are often granted boons.
Boons can come in many forms. It may be a minor power that a character can manifest upon demand, such as purifying water or granting light upon command. It might be a continuous effect, such as a halo of positive energy that acts like armor. But one way or another, the boon is almost always related to the deity's domain.