The 14th century saw the most change in the appearance of medieval armor, virtually changing from all chainmaille (fabric made of small interlocking rings) to all plate armor (large pieces of metal). It was a time of great political upheaval which saw the development of mercenary companies who worked as brigands (a type of bandit) when unemployed. The Hundred Years War took place, which didn’t actually last a hundred years. The feudal system exceeded it’s usefulness and was phased out and due, in large part to economics, there was a large change in the knight and his equipment. The 14th century saw the increase in use of plate, latten (a copper alloy), whalebone, cuirboulli (hardened leather), iron and steel in armor.
The big question is, “Which came first? The chicken or the egg?” Weapons developed along with armor. This was the beginning of the use of the two handed axe, mace, thrusting swords, two handed swords and the longbow with it’s high firing rate and excellent penetration abilities.