There were the knights, gleaming in richly wrought plate-armor, colored plumes waving above their burnished sallets. Their steeds, caparisoned with silk, lacquered leather and gold buckles, caracoled and curvetted as their riders put them through their paces. The early light struck glints from lance-points that rose like a forest above the array, their pennons flowing in the breeze.> - Black Colossus
Lances are the shock weapon of the cavalry charge and they have the ability to break armies at the first engagement.
Despite being heavy and unwieldy, lances are always the first choice of weapon for cavalry (with the exception of the uniquely talented Hyrkanian horse archers).
True bravery is the ability to stand and face a cavalry charge - a bristling forest of lances being driven towards the line by hard-faced men on screaming horses.
Lances rarely survive first contact, breaking or splintering or being lodged through the chest of a foe. Most cavalry carry a secondary weapon into battle for this reason.