Lewis & Short

dŭcĭānus, a, um, adj. [dux], of or belonging to a leader or commander (late Lat.): officium, Cod. Th. 15, 11, 2: apparitores, ib. 11, 25, 1: judicium, Cod. Just. 7, 62, 38.
Subst.: ducianus, i, m., a commander’s servant, Cod. Th. 7, 16, 3; Cod. Just. 1, 27, 2, § 8.