[Dedas]

Yes, I agree Quantum, some weapons are worse than others in every way except one - in cost. In some cases cost is a factor, in others not so much. That is what I mean with niche as well. Now and then you don't need that extra damage or that extra attack, you will be better of with more troops or more weapons instead. Quantity over quality if you will.
But that isn't black or white, quality will conquer quantity with hardly any loses at some levels. So few loses will it take that it would have been better to go with quality. The key word is of course efficiency, but that is relative to a number of things.

As always it is good to come up with an example:
What do you prefer:
4 Black lords kitted with low class magic items.?
Or
1 Black lord kitted with high class items?

The answer is of course: "it depends". Maybe you could take 4 provinces at once with the low class BL, and only one with the one BL. But maybe the four low class BL can't take one thug? What do you prefer? With those extra provinces you might find gems faster to kit out an even better BL.
So you looking at the whole picture and from there drawing good conclusion (not the best because it is almost impossible to predict exactly how humans will react to your decisions) on how to act seems like a good way to play. Trying to approximate what is the perfect move.