The priest should be a support character, but quiet prevents it from being that in endgame dungeons.
One fix would be to make the manor set have a set bonus that makes the class immune to quiet.
Another one is making quiet have another effect on priests, like everytime a quiet-shot hits it, your mana gets halved instead of taken away completely.
In general I think a priest should never be completely prohibited from healing.
peace out, have a great day