Hits on a basic problem throughout the game. Bottom line, its almost always the best idea to just shove the best armor and weapons on someone and shove them out the door. There's no penalty to loading up your archers with plate armor other than some extra resource costs, which given the fact that I'm almost never constrained by resources is not much of a penalty. There's no real trade off in weapons, there almost always a 'right' choice at any tech level. Who's using axes when you can equip someone with a 15 attack war staff?
Other games usually handle this in some sort of rock paper scissors format: build a lot of horsemen with heavy plate armor, well my extremely cheep, rapidly produced pikemen get +100% attack vs. your horsemen, maybe you should use something else. Like pikemen? well watch out for my heavy swordsmen, they may be expensive but they can decimate pikemen in close combat. Like swordsmen? well my crossbowmen can wollup them from afar. Like crossbowmen? watch my horsemen tear them apart, and we circle back... Not saying that Elemental should adopt such a basic balancing strategy, but currently there is almost no strategic differentiation at all. Their almost always a clearly 'best' unit and you'd be a fool to use anything else.
There is a little differentiation put in by shields and one handed weapons vs. two handed, but this is so minor as to be nearly inconsequential. There's also some light regarding the possible changes around initiative based combat so that maybe a 'fast' unit might be better against lightly armored foes, and a 'slow' unit might be better against heave armor. However, none of this in my mind leads to a really interesting parry, counter parry, riposte, strike... back and forth sort of strategic thinking. We generally just get two armored dudes with swords bashing at each other, the one with the lower tech loses. Unless of course one side has arcane arrow, in which case the other side always loses...