I have doubts about that whole 'hard to train' thing. It used to be very hard to train military skills compared to everything else. I'm not sure when that changed (either in vanilla, MW or Reborn), but now, with the current reborn version, simply making squads of 2-3, and letting them train as they want for a few months helps tremendously. Individual training, demonstrations, especially sparring work well.
They may not become legendary overnight, but I tend to quickly train a couple of guys to a reliable level.
So yes, I think the quality of the armor matters far more than its weight, and heavier weapons are almost always better. You WILL use your axes and swords for blunt damage after all: pommel strikes, flat of the blade, bone breaking through armor, just to name a few. Ranged weapons are in a league of their own of course, but who makes an orichalcum crossbow anyway?