I was testing out a theory today regarding color changing. I believe you can bypass the three color system if you arrange varientmeshdefinition entries right and if you have the base texture in a color. I know in shield designs, if you add a color to the pattern, it overrides the system. L'algile has done this to great effect as see here.
Spoiler Alert, click show to read: 





I wanted to test this principle out with other armor parts. I too the texture file "hellenic_companion_cloak_diffuse" and just bluntly turned it green. I was expecting all the cloaks to be green. Instead it became a fourth variation! I looked in the variant definitions for any insight on why it did that. Turns out the Companion Cavalry has three entries under cloaks. Two are the above name, the other is a celtic cloak entry. i'm guessing that because that was still white, the faction colors were still there. I'm going to look into this some more, I believe if you add enough cloak textures with different colors you can effectively make color variations more diverse beyond the standard three. Stay tuned for further investigations.