1) Cannon 2) Lower cannon 3) Medieval armour 4) Western plate armour 
Vambraces (French: avant-bras, Polish: karwasz, sometimes known as lower cannons in the Middle Ages) or forearm guards are tubular or gutter defences for the forearm worn as part of a suit of plate armour. Vambraces may be worn with or without separate couters in a full suit of medieval armour. The term originates in the early 14th century. They w...
armour for the forearm
• (n.) The piece designed to protect the arm from the elbow to the wrist.
See armour.
Vam'brace noun [ See Vantbrass .] (Anc. Armor) The piece designed to protect the arm from the elbow to the wrist. 
armor used to protect the forearm
[n] - cannon of plate armor protecting the forearm
lower cannon noun cannon of plate armor protecting the forearm
Plate defence for the arm see upper cannon couter and lower cannon.