Guisarme

Guisarme (or gesa, gisarme, gysarme, jasarme, giserne or bisarme), a European polearm that evolved from the war scythe or military scythe. The Guisarme differs from the peasant war scythe by an additional thrusting blade at the back or the tip of the scythe blade. Improvised polearms of this type could be made quickly and cheaply by reforging available scythe blades, which is why they were very common in Europe from the 11th to the 19th century.
Source: Meyers Großes Konversations-Lexikon, 6. Auflage 1905–1909