1
Bronze shield of King Pharnakes of Pontus, 2nd century BCE
(media.kbin.social)
https://en.wikipedia.org/wiki/File:Shield_Pharnakes_Getty_Villa_80.AC.60.jpg
Bronze? Heavy AF. You have to have muscles to be waving that thing around for any amount of time. So mostly ornamental? I don't have a clear picture of which periods kings were actually active in combat. Some periods and places, it seems common; others, they were more rear field commanders.
Probably mostly ornamental.
Just a magazine for everyone to share artifacts and replicas for the historically-inclined to admire!