Frogboy, you're looking for a level of complexity somewhere between something like Civ IV or Elven Legacy and Dominions 3, right? Far as I can tell from the game specs so far, the army building/development is going to be:
Take guys (and gals).
Give them equipment.
Upgrade equipment as resources/tech allows.
That means that you are always going to have at least 3 different types of stats interacting (possibly 4 when you deal with mounts).
Natural stats of guys.
Stats of Weapons/Armor.
Benefits of training/experience.
and possibly stats of mount.
All those factors should produce interesting considerations - wargamers call them "guns or butter" decisions. Ideally, the whole thing should be understandable enough that somebody who doesn't really want to get deep into the tactical considerations can create an army with relatively understandable units (archers, cavalry, pikes, swordsmen), go out, and do just fine, but the hard-core number-cruncher can build specialized units to exploit the strengths/weaknesses of their own or the enemies armies.
You also want this to be relatively moddable. Of course, that doesn't mean it has to be simple - Dominions 3 is anything but simple, but highly moddable, because it has a lot of factors that combine to create interesting and sometimes unexpected results.
Also, guys, I don't think that when Frogboy is talking about stacking damage types, that's he's talking about it in the context of army creation. He's talking about it in the context of modding and enchanting. You would not be able to build super-weapons with 5 piercing, 5 crushing, range 100, but you could mod it (hopefully making it ridiculously expensive and high-tech/rare resource based).
Personally, I would really like to be see - hey, I have the metal/tech skills to make chainmail now - my light spearmen unit is in supply range (another good application of the Outpost/supply mechanism). Click on the spearmen, hit "Upgrade Equipment" - see a list of available gear, as well as cost in materials/coins (based on the size of the unit and the cost of the gear) - hit "Chainmail" - resources come off my global, spearmen are better, everyone is happy.
That would also allow me to adjust my armies on the fly to fight certain opponents - got a horde of light-armored goblins - lets go with tower shields and shortswords for my unit. Fighting heavily armored trolls - let's switch to halberds or 2-handed axes.