References can also be found in the 1.0 throwing weapon, Exorcism Beans, as well as in the titles of a couple levequests, A Little Constructive Exorcism and An Old Fashioned Exorcism.
Thank you so much, this is very helpful! It seems it's just old fashion and done the same way as well know it. Interesting to know white mages can perform the ritual, it always seemed like it was a black Mage thing.