@LukeAlmighty Looks like armor to bridge the gap and protect the armpit.
All I could find for that was Rondel(s) which is a disc shaped piece that protects that gap.
This might just be a fantasy thing, but I'm sure it has a name.
CC @vitalis
@JedDrudge @anokasion @GrungeQueef this one got the comment "if the emperor had listened to malcador"
I draw, code, and make memes sometimes.