Pieces that typically protect the upper arms and/or underarms are Spaulders, Pauldrons, Gaurdbraces, and Besagews. These pieces are as diverse as the people who wear them. Spaulders are usually simpler than Pauldrons and are a series of plates that cover the shoulder and upper arm, but not the underarm. Pauldrons cover the shoulder, and can cover the underarm and even parts of the chest and/or back. A Gaurdbrace is an addition to the Pauldrons that covers the front of the shoulder. Besagews are small circular pieces that protect the armpits, and are typically worn with Spaulders. Designs for these pieces range simple to extremely elaborate.
Rerebraces (upper cannon), Vambraces (lower cannon) and Cowters (Couter) are pieces of armor that protect the arms. Rerebraces cover the upper arm and extend from the elbow to the shoulder while Vambraces cover the forearm. Cowters protect the elbows and can be designed typically in a pointed fashion with “floating articulation”, achieved by being sewn onto the gambeson (padded long-sleeve shirt worn under your armor). Cowters can have regular articulation.