I don't know how armor penalty is calculated right now, but i guess it works similar to the old patch armor penalty (head and hands x3 body and legs x1).
I suggest that melee and ranged should calculate this in different way.
Melee - (head and hands x2 body and legs x1)
Ranged (head and hands x4 body and legs x1)
(or use different mechanic to get the result where ranged troops are penalized more than melee troops for taking full helmets and heavy gauntlets, which will result in using leather gloves tops and helmets up to 1.7 for ranged troops).
