What defines a troop type as Heavy, Medium or Light?
I'm assuming it has something to do with speed, and I always assumed that more heavily armoured the unit the more likley it was to be classed as Heavy. But recently, I've been seeing Armoured MF and I've seen a lot of Protected HF, so now I'm not so sure
Finally, is there any difference combat-wise between Heavy vs Medium? I had, in principle tried to steer clear of MF in my armies, but if the troop type is 'cosmetic' then maybe I've been making a mistake!
All input gratefully received.

