From Halopedia, the Halo wiki
A Minor Prophet, also known as a Precentor, was a title used by San'Shyuum politicians of the Covenant. Compared to other titles used by the species, the title of Minor Prophet was comparatively low in San'Shyuum society.
Powers and functions
Minor Prophets were generally religious officials appointed to ministry-sponsored Covenant fleets to serve as advisors in matters of faith. They served as the exclusive commanders of Covenant procurator vessels such as the Mjern-pattern agricultural support ship, working as a religious authority, logistics coordinator and mediator for the fleet's Supreme Commander. Their presence in the fleet was generally the only voice in the fleet able to challenge the decrees of the armada's Supreme Commander, in no small part due to their direct communication with the Hierarchs and direct reports to the Covenant High Council.
Minor Prophets also occasionally assigned themselves to a fleet. Some Minor Prophets served aboard Mjern-pattern agricultural support ship, commanding the vessels' crews of Unggoy, Huragok, and Sangheili. A Minor Prophet had the power to take control of an entire fleet if a object of great religious value was encountered and even force a Supreme Commander or a Fleet Master to relinquish command; as was the case when the Minor Prophet of Stewardship temporarily took control of the Fleet of Particular Justice when Installation 04 was discovered.
List of appearances