Pauldron

A pauldron (sometimes spelled pouldron or powldron) is a component of plate armor that evolved from spaulders in the 15th century.

The pauldron would typically be cut shorter to allow this rest without restricting arm mobility or the rider's protection.

Typical tournament armor for jousting would be padded with cloth to minimize injury from an opponent's lance and prevent the metal of the pauldron from scraping against the breastplate.

In fact, knights in this era could be padded to the point where they look "more wide than tall" compared to contemporary depictions of jousting armor.

Such a feature would be impractical in combat, as performing any action that requires raising an arm risks a spike poking the wearer in the head.