Purified

 is a passive skill in Outward.

Acquired From
Can be learned after completing the Holy Mission faction quest Questions and Corruption.

Elatt will give you the option to claim his blessing for yourself, which will give you the buff, or to give Oliele the blessing, which will give you novice robes and a recipe for Marshmelon Tartine. Its unclear whether anything else happens when Oliele gets the blessing.