Sorry Glen, read now only.
1) I plan to paint one side only, light from the front left side as these flats will be exposed in a frame, not in a diorama
2) Colours are set by the coat of arms for the most; your figure is Jacques III de Heilly, killed at Agincourt, his coat of arms is "De gueules, à une bande fusellée d'or", so colours are Red and Yellow (I can't attach figure from my laptop now).
Jacques III of Créquy, sun of Jacques II de Créquy, lord of Heilly, served the duke of Burgundy Jean Sans Peur of which he was one of the main captains. In 1408, he marched against the Liege to restore their bishop on the episcopal seat. In 1413, he was made Lieutenant General of Guyenne. As a prisoner in Bordeaux, he fled. He took part in the battle of Agincourt in 1415 and was killed by the English, on the grounds that, against his word, he had escaped from his prison.
The nuance of red and yellow you wish to give is up to you, either bright, saturated or not; the colours we hav today from historical flags an paintings have been somewhat been faded by exposure to the aging and sunlight.