Fleetmaster
From Halopedia, the Halo wiki
Fleet Master is the highest version of Zealot except for Supreme Commander. Normally, they acts as the Ship Master, and controls only ship. But, when only a little part of a fleet needs to do an special mission or simply are needed elsewhere away from the rest of the fleet, a Fleet Master commands those few ships during that task.
Only one Fleet Master is officially known, and that's Voro 'Mantakree. He commanded a small task force to Onyx in order to follow the Covenant Destroyer Bloodied Spirit.