Trivia: This film is actually the second version of "Exorcist: The Beginning" to be filmed and completed. But upon seeing the first version, the studio protested the film was based too much on the characters and wasn't the gore-fest they wanted, so they hired a new director and reshot the entire movie with a different script. The original version of the movie was recently released on video as "Dominion: Prequel to the Exorcist."
Trivia: Stellan Skarsgard, at age 53 when filming this movie, is nearly a decade older than Max von Sydow was at the time of filming the original movie (age 44), but is playing a younger version of the character.
Answer: I do. It's just the Latin form of the Ritual Absolution in the Initial Rites from the Mass, applied to the second singular person (it is said with "us", instead of "you"), though it should not be used there with Sarah. In those situations, the proper absolution is the one that belongs to the Sacrament of Reconciliation or, instead, a simple blessing. The translation is: May Almighty God have mercy on you, forgive your sins and lead you to eternal life.