legate
(lat. legatus). The senatorial ambassador a) to foreign nations or b) to military commanders, in which case he assumed command. He was considered a functionary, since he was under the commands of the Senate; he was also a sacred person.In later periods, legate was named the representative sent to a foreign land, and such was the title of the head of the Italian communities in Byzantine Constantinople. The representatives of the Pope empowered for the settlement of ecclesiastical matters were also called legates.

megas doukas
The commander of the Byzantine fleet. In the Late Byzantine period, the title of the megas doukas was assigned to the highest officials of the imperial administration.