1) Military rank of ancient Rome 
Vexillarius can mean one of three things: First, a vexillarius or vexillifer was one of the signiferi in a Roman legion. His duty was to carry the vexillum, a military standard displaying the name and emblem of the legion. This standard consisted of a woven fabric banner, hung on a crossbar attached to a pole or lance. It was used by both infantry...
A - standardbearer. B - soldier serving in a vexillatio .
The senior standard-bearer of an ala who carried the vexillus or vexillum. Also the name of a soldier serving in a vexillatio. 
vexillarius A standard-bearer, or under the Roman empire, `the oldest class of veterans”.