[thejeff]

I like commanders with standards. Or just a general morale boost: We are all elite troops! And we know it!
Or just for the Black Plate troops. Boost their skills too. Elite troops get the best armor.

Make it the best mundane armor. It's supposed to be Ulm's great discovery, but the consensus is the chain mail troops are better. Boost the protection, drop the fatigue. Make those troops dangerous in the early game. They'll still fall to double bless, or elephants, or SC pretenders, but everyone else should have serious problems facing them with troops.

Sidetracked, I was supposed to be commenting on jaif's ideas.
1) Mini thugs and standards. I like.

2) Not really modable. No nation specific item changes.

3) Nor this. No way I know of to mod spells that upgrade items.
Both would require changes to the game engine.

But, you could fake some of it, by making spells that summon troops/commanders with that better armor. Conceptually, the troop are recruited normally and the gem cost goes to the armor, but mechanically it's a summon.

They should be cheap, because they're still vulnerable humans under the gear. The troops will be little more than a good meat shield in the mid game and the commanders low-end thugs, but still a nice addition.