The plethora of polearms in mediæval Europe is vast enough to be not just confusing but comical; a state exacerbated by the different names various regions would have for the same or similar arms. The bill hook is simple in this regard: it was a very English weapon, and it was the holy terror of the Continent for over three hundred years; the English army retained it and conquered even when the rest of Europe moved to pike to supplement their guns. George Silver, although a contrary curmudgeon, considered the bill hook unparalleled as a weapon, and with some reason; from what we know it certainly appears to have been one of the better polearm designs.
The blade of the bill hook is broad and straight until it comes to an end in a wide hook shaped almost like a Phrygian cap. This hook is variously employed, but especially — and herein lies its superiority to the common pole-ax and other polearms* — to pull a rider off his mount, then efficiently murder him by means of the armor-punching point of it. It also served well for clearing spears and pikes, making for a felicitous combination of functions that most polearms aspired to, but never attained.