The whole weapon promotion should be done away with IMO.
Copper gives you axemen
Iron gives you macemen.
It shouldn't mean just because you have Iron, that Warriors weilding wooden clubs should get stronger. Nothing is free in life.
make them pay for their upgrades.
If need be, make Mithril a pre requisite to show its special quality in the teir 4 melee units
I've seen this objection quite a bit, but IMHO the resource upgrades are logical. If you have Copper, why wouldn't you make Copper clubs? The same with the other metals as well. Training and weaponry is one bonus (ie;a warrior compared to an axeman), while what the weopons are made of is another. It is just one unique concept among many in this mod that should stay!
Great Work on an AWESOME MOD!