Human warriors seek to protect themselves. With the discovery and development of Bronze there was suddenly a way of protecting the head and the body of a soldier. Those societies that were able to use Bronze soon began to flex their particular muscle against others that opposed them. This was the beginnings of armour, something that we still try and develop today. These early warriors found an advantage on the battlefield but it was to be short lived. After the discovery of iron ore and the fact it could be melted and shaped into something stronger than bronze the new age of armour began.
The biggest advance that iron brought was the chain mail vest and suit. This was a series of heavy linked rings that could still give the fighter movement. It was tiring to wear, especially as it was combined with a heavy shield, also iron bound.
It was the Blacksmith and the Armourer that were responsible. Much like a modern set of Tapping Machines like those from https://www.cotswold-machinery-sales.co.uk/roscamat/electric-tapping-machines/roscamat-mosquito-electric-tapping-machine/ this was precise work requiring great artifice. The age of plate mail brings us to the golden age of armour. Knights would go into battle fully covered in this mighty metal suit that was surprisingly mobile.