Generally I dont mind the clothes colours as it makes allies and enemies easily distinguisable. But when its N Emp vs E Emp you have light purple vs purpley-blue
Maybe the eastern empire's clothes should be given much more saturation, so they are a darker and richer purple, or just make one of them a different colour all together (e.g. white or black).
Black (or very dark purple) clothes would even fit the Eastern empire if you claim it represents them in mourning over their dead emperor.