gisarme
A type of polearm having a spearhead and a reverse hooked spike on the back.
The Gisarme called also gisaring, and, by Fleta, sisarmes is likewise an ancient weapon of the staff kind, but of what for seems doubtful.
Where it comes from
From Middle English gisarme, from Old French guisarme; compare modern French guisarme.
Adapted from the Wiktionary entry gisarme (CC BY-SA 4.0).