I was designing some units today and the armor materials costs is prohibitively high.

I'm on turn 123 and my only material income are the workshops in my cities. After equipping all of the basic leather armor, the material costs for a unit are in the 60s for a defense value of 6. Comparing this to the material costs of shortsword (4 I believe) gives the unit an attack rating of 8.

On a another note, the plate of the titans (as of beta 3) had no material cost or research requirement. This could lead to a very dangerous combination as this chestpiece provided 6 defense with no additional cost for the unit. While master armor smiths is supposed to be an advantage, it seems a little too powerful in its current state.

Once again I'd like to thank Stardock for letting the public into this phase of the beta. Hopefully this suggestion helps.