Sorry if this is kind of too long to be in "Crazy" suggestions, but I'd really like to see this be made!
I thought of a really good defender faction: The Pigmask Empire.
You might know these from the title Mother 3 or Earthbound. Or even Garry's Mod Ultimate Chimera Hunt.
These guys I found really good and I would find it a really good idea if you made it a defender faction, full with their uniforms. The highest rank uniform (The Colonel uniform) would cost the highest, and the Enlist uniform would be the cheapest.
I thought their weapons could be swords (Two handed and 1 handed). And some form of rifles, muskets or just bows and arrows to balance out the aspect that there would be both ranged and close-quarter weapons
The armor could be their original uniforms and, starting from the Enlist up to Colonel, the armors would each have different stats. The higher ranks having higher armor etc.
The classes could vary up to all the Ranks, however, it would cost more money to get a higher rank uniform than what you already have. To add to the aspect that they are indeed ranks. And vary in the weapons each rank has. For example, Majors and Colonels could have bows/muskets/rifles, while the lower ranks only have melee weapons and (Possibly) Low quality ranged bows.
The weapon powers should too vary to signify rank and power in each of the classes.
If you could actually make this, I, and my good friend, would be ever so greatful as we love these Pigmasks so much. So, just try thinking about it. If it's possible to model the armor and helmets.
If you have no idea who they are, try googling in images. You'll find pictures of their uniforms etc.
I tried to make it as detailed as possible so you have an idea of what would be really good and what we would like.