From the Beta footage I've seen, unit's accessories are the colour of the team. (for instance, when Vlandian Sergeants are in the light-colour-version, their items are yellow instead of red) The only exceptions I've seen are the Aserai Guard's belt (always blue/purple) and some Huskarl's trousers (red lines)
Aside from these, I reckon troops will be of the same colour-scheme as the banner