The ancient Greeks used to decorate the symbols and representations and considered samples honors.
Even knowing the words that say the Spartan to their children before the battle: "or when or on Tash," showing how offensive thought was abandoned on the battlefield. The ripsaspis (who threw the shield and leaving) only benefit general disapproval and criminal punishment.
The shield is the oldest defensive weapon. The shape of and the construction was different from place to place and from year to year. So we have wood, iron, leather, brass and even rectangular, round, triangular etc.