Fian Champion as in the specific tier 6 unit. Turning them into common troops would mean losing them in particular. For all the justified complaints about how OP archers currently are, I still love the idea of a super elite archer unit, and I'd hate if they went away.
Also, I disagree with the idea that Cataphracts should be the absolute best shock cavalry. One of Vlandia's strengths is meant to be their shock cavalry, so if anything their Banner Knight ought to be the best, at least in terms of just hammering people. In practice they're somewhat more devastating than other lancers at bullying infantry, just not in any appreciable way seeing that they all suck right now. In my mind, cataphracts should bring extremely heavy armour and a very long lance to the table. Make them stand out as the tankiest unit, if less potent on the offence.
And considering how badly the Empire powercreeps on almost everything with their roster, I don't want to have the best shock cavalry on top of that.
All, that aside, I don't see the issue with an expanded noble tree. Of course it's not a huge priority, and I'd rather devs spend their time refining the combat AI and equipment first. But with more noble troops we can actually please more people.