This word for a banner or pennant hung from a crossbar has close relatives in several modern European languages.
It’s a variation of the older gonfanon that can be traced to an ancient Teutonic term that meant a war banner. The second part of that word has turned into modern German Fahne, a flag, and also into the obsolete English fane for a flag or a weathercock, which has become our vane. By itself, fanon is a shoulder cape worn by the Pope during solemn mass.
Gonfalons usually contain elaborately decorated images or emblems, such as the coat of arms of an organisation. They frequently have swallow tails or streamers attached. Almost any formal procession, such as that of a church, a trade union or university, will have members carrying gonfalons. Historically, a gonfalon was a standard of the medieval Italian republics.
The sun was setting over the western mountains when the last dhow entered the bay. This was the largest of them all, and at the peak of her stubby mast she flew the snarling leopard head gonfalon and the gaudy colours of the House of Trok Uruk.
Warlock, by Wilbur Smith, 2001.