pennon (n.)

"long, narrow flag" (often triangular or swallow-tailed, attached to a lance and having distinguishing markings), late 14c., penoun, from Old French penon "feathers of an arrow; streamer, flag, banner," from penne "feather," from Latin penna "feather" (from PIE root *pet- "to rush, to fly"). In medieval Europe, the flag of a knight-bachelor or one who has not reached the dignity of a banneret.