A hurlbat (or whirlbat, whorlbat) is a weapon of unclear original definition. Older reference works refer to it largely as a type of club, either held in the hand or thrown. Modern usage appears to refer to a type of throwing-axe.
Thus, in the Middle Ages, the term referred to an aklys-type spiked club attached to a string, used for throwing and perhaps as target in swordsmanship training. After 1700, however, this meaning became quickly obscure, and eventually the "hurlbat" was imagined as a bludgeoning weapon that was swung, not thrown.