Navarch was a religious title outside the command structure of the Bajoran Militia. A navarch was expected to report directly to the Prophets.
In early 2370, the title was given to the resistance hero Li Nalas by the Bajoran Chamber of Ministers following his rescue from the Hutet labor camp on Cardassia IV. The rank was specifically created for Li, as no other title was considered worthy of his name. (DS9: "The Homecoming", "The Circle")
"Navarch" is of Greek origin and means "leader of the ships". The word admiral is translated in Greek as "navarchos."
The relationship between Li Nalas' insignia, which appeared to be a Bajoran emblem with a black segment on top, and his title was not clear from the episode.