I don't have much time right now, but before I explain it in detail later I want to point out the major factors early:
1. Agreeing to most of my predecessors Morale should be a most basic value, that should change throughout a lot of the battle by many factors (experience of the unit, win/loss, difference in numbers, direct hits, a lot of magic, creatures that produce fear/terror, there is a lot of space.) The effects of Moral could be different, but should result in a gradual loss of overall fighting capability (including mobility) maybe up to the point of fleeing. You also wished to stronger include experience, well here is the best spot to do so. Be it a factor to decreas morale loss, more morale to begin with, faster morale regain or any combination of it, experience should affect it. (Because that is exactly where in our real world experience had the biggest effect)
2. Rock, Paper, Scissors should NOT be used in a artificial way. The game design should always be, that the classical balance from our real world (examples: cavalry beats archers most cases), RESULTS from the abilities and attributes of the units. I give classical examples. Cavalry shouldn't get a bonus against archers because they are cavalry against archers. They should be good at it, because they are fast and can outflank enemy positions, and because archers tend to be vulnerable to charges because of their lack of shields and formation. Another examples is spears against cavalry. Spears shouldnt just do bonus damage to cavalry. They tend to work against cavalry because they were long and cavalry tends to impale itself, so maybe give them something like a first strike ability and/or a damage bonus against a charging unit, that scales with that unit's charge bonus. I hope you understand the idea.
3. The battle needs to go far beyond the basic attributes, that are currently implemented now. (This is my personal opinion). As I understand you devs want to give the players a feeling that their "Zhaak'Ye Archers" or their their "Hounds of Karesh", or other units and their combinations that they come up with, feel special to them. You CANNOT reach that with a simple attribute system as it is implemented now. If you design a unit that simply has the best of everything (maybe except mobility) and anyone can do without spending a single thought on it, it means nothing in the end.
In order to fix that, you either need to complexify the base system a lot. You do that either by complexing the base system: Damage Types likes Blunt, Piercing, Slashing, whatever, just an example, the corresponding armor types too then.Chainmail is nice against slashing and ineffective to blunt and piercing, to give an example. Special abilities tied to weapons (first strike, charge value, one-time usables etc).
Or you promise us a very complex and distinctive magic enchanting system for units or units equipment, better both. I will just give one example and that is the well known Master of Magic. The combinations of enchantment-spells on units (and their running costs, so you had a tradeoff), are up to today unmatched in their complexity and fun to come up with.
To my personal liking I would want to see both, a complex equip-based base system with damage types and enchanting options (with a tradeoff), for equip and units respectively.
4. Also agreeing to a predecessor without many words: You at LEAST to differentiate between MAGIC and PHYSICAL damage types. Personally I think an element-system should be included (Its called Elemental after all isnt it )
Alright, that's it for now, I hope that my argumentation is plausible to you,
Have a nice day,