Ya know I do think limiting tier 2, ie what will be standard infantry to only leather armour is a bit crazy. I am pretty sure the standard armour for your average soldier in the middle ages involved metal.
I am not that big a fan of all the other restrictions either. I like the potential for upgrades that has been brought in but you can easily devise a system for upgrades which does not include so many arbitrary restrictions.
I was hoping for a wide variety of interesting troops though and this seems to be getting restricted un-necessarily. Sure it might be easier to balance if you force everyone to follow these rules but I liked the potential for originality.
PS
Nike, he meant leg protection given by that armour. I think