I think another good aspect of a system like this is that it would clearly illustrate the difference between training and equipment when it comes to troops.
Ideally, Attack and Evasion/Defense (whatever you want to call it) should be trainable; something linked to stats.
Meanwhile, Damage and Armor should both be based mainly on equipment, I.E. Weapon Damage and Armor Rating. (With Stats like Strength and Constitution factoring in, of course.)
In this case, if you want troops who have higher Attack and Evasion/Defense, you need to spend more time than money training them...but you could also equip them and go the route of more money/resources and less time, to 'mass produce' legions of peasant troops who have equipment: sort of like the difference between crossbowmen, and longbow-men.
It also allows you to tweak what you want your troops to do and be good at much better; how do they react to an incoming volley of arrows: run for cover, or stand and raise their shields? (Ideally Shields should be a form of Armor, stack-able with other armors.)
Furthermore, when it comes to Sovereigns and Heroes, it gives you more room for customization and ability differentiation; whether you want to be able to dodge and weave, avoiding spells or area attacks, or absorbing them...I imagine resource/money poor sovereigns are more likely to go the Evasion/Attack route rather than the equipment heavy route.
Lastly, a very good contrast you have heavily armored shock-troops versus light, quick 'assassin' type troops. One type is slower, can absorb attacks, is mostly immune to low-damage attacks, area or otherwise, and costs more up-front. The other type is faster, avoids attacks, and has to be worried about things like large area attacks or rapid-fire low-damage attacks, and takes time to gain exp and become more useful, rather than costing more up-front.
