Now, I don't quite expect this to be implemented. It's just an idea off the top of my head. Each army would have its own logo/emblem on their armor, as well as colors/patterns. There are a ton of pros to this, such as that your armor would be more unique and you could differ armies' units from each other, while they're the same race. The only con is really that it takes a long time to create.
Anyways, just throwing this idea out there.