Coat of Arms of Coucy - messengers badge?

[AHorsa]

Hi there,

although it is not an arm or armour but a coat of arms, I hope someone can help here. I recently got this coat of arms. It measures 7.5 x 6cm and weights 35 g. The shield itselfs seems to be made from bronze or copper with an attached layer of silver or another "white" metal (see also 3rd image). According the paper note on the backside it was found in the river of Seine.

The CoA is the one of the Maison de Coucy: https://fr.wikipedia.org/wiki/Maison_de_Coucy

It seems that the potentially blue parts are already gone. I can´t tell from what material the red areas are made. The white metal represents the white areas of the blason.

Is it possible that this shield is a messengers badge?
I found some examples here (which of course are larger and from much better quality):
https://www.metmuseum.org/search-results#!/search?q=messenger%20badge

What do you think about its possible age?

Looking forward to your comments!

Best regards
Andreas