The divellion or dibellion (Greek: διβέλλιον) was a symbol of the late Byzantine Empire, the Emperor's personal banner. It was carried by the skouterios ("shield-bearer"), alongside the Imperial shield, on official events. Emperor Stefan Dušan of Serbia (r. 1331–55) also adopted the Imperial divellion, which was purple and had a golden cross in the center.
References
Divellion Wikipedia(Text) CC BY-SA