[absolootezer0]

wouldn't ceremonial armour also tend to be armour of the way high ups in the aristocracy, who wouldn't have had the armour comissioned until they were in their seat of power and were older? i've noticed that people tend to shrink as they get older, which may be a contributing factor.

[Post-Neolithic]

This site has quite a few articles on armor, both Ceremonial and Battle, from as far back as the Roman Empire.Hopefully this will answer some of your questions as well as add to your knowledge. It's a fairly long read, but the site does seem to contain quite a few gems about Armor Decoration.

The Decoration of European Armor