I think the wording means the Ritual points are individual per priest, and each Priest is walking through the battle constantly chanting their own hymns and prayers. "on a roll of 2+, your PRIEST gains that many ritual points" They already have a precedent for a Player gaining points (Blood Tithe in Khorne, also command points), and this is worded as the individual Priest gaining them, so per-Priest makes sense in that regard.