The armor weight and ranged problem:
Light armor should be high elemental defense and low physical
Medium should be low elemental a high physical
Heavy both high
So, now you have, something like:
melee > 3x damage > light
melee > 1x damage > medium
melee > 2x damage > medium or light (splitting damage types)
ranged (bow) > 3x damage > light (if the bow is not splitting damage types)
ranged (bow) > 1x damage > med (if the bow is not splitting damage types)
ranged (bow) > 2x damage > light and medium (if they split damage types)
ranged (mage) > 3x damage > med
ranged (mage) > 1x damage > light
tank > tank
healers > take away the penalty in heals for medium, now they can chosse to be safer against light melees, ranged, or mages by choosing medium or light)
Now, bow is an all around damage, good damage on every one but tanks, but wont explode anyone in 2-3 shots, relly on their mobilty and positioning to be effective. And could make a point in medium armor, loosing a bit of damage, but not beeing squishy and as mobile
Fire mages are great damage against medium (beeing it a healer, melee or ranged), and weak against light
Light melee deal a ton of damage against ranged light, mages, bows, healers (if they run light)
Medium melee would deal a lot of damage to light melee (light melee would really relly on its mobilty to be able to win against medium melee