The Halberd was the weapon of choice for unmounted infantry to fight cavalry. The spearhead at the tip would be used to balk horses and knock knights off their mounts, with the forward axe-blade or pick to pierce armor and deliver the killing blow.
Halberds were widely used by formations of foot soldiers due to its length and effectiveness at separating mounted knights from their horses. It was also easier to mass-produce and required less training to wield skillfully. Halberds were commonplace by the end of the medieval age, and were seen in the hands of police forces and soldiers long into the Renaissance.
A Japanese analogue to the Halberd would be the Naginata, a long polearm with a slashing blade at the end (though with no spearhead). It was often associated with female samurai and Buddhist monks.