Hello Glen,
I think he wears an armor like on the "La Rochelle" picture, because he was very unpopular in France and
involved in the 30-years-war, the war against the Huguenots, etc. So I would wear an armor this time, too.
There are not many uniforms in the 30-years-war.
Private he wears the habit of a catholic cardinal without armor. As cardinal he had to hold a lot of wor ships
and audiences.
So I think his catholic habit was his "uniform".
Best regards
Michael