Quote Originally Posted by Kobal2fr
Well, we don't know for *certain*. There is an entry for mount type (ie horse, heavy horse, mailed horse, barded horse) in the unit files, but since we only get that, and not the actual battlefield mechanics, we can't be sure wether it's factored in, or wether it's just to tell the game which type of horse to display.

I guess I'll have to test this more thoroughly when I have the time .
IIRC the mounts armor is related to the units armor.