As with my post on Dynasties. I have a few problems with Champions the way they are currently implemented in the game.

Currently Champions are wandering heroes, that you can hire, equip, potentially marry and imblue with essence and ultimately use on quests for your faction.

However, the cost for these units is currently prohibitive considering their benefits.

First, from a cost standpoint. Each hero requires gildar to recruit. Any hero beyond a 1st level champion costs usually too much to recruit and a party of them is too expensive for the game economy. Cost to equip a single champion, currently can be exorbitant. Consider, equipping a 1st level champion with a short sword, leather cuirass, leather armlets, leather helm and leather leg greaves will cost you an additional 360 gildar. A single soldier with the same equipment costs 23 gildar. So the question you need to ask yourself is a single champion worth 15.5 soldiers?  Obviously, there is a cost disconnect between the shop value of common equipment and it's production equivalent which needs to be addressed.

Second, each champion can be imbued with essense to make them magic users. However, with the current magic system, the sovereigns cost in permanent mana loss compared to the minor benefit you get from the champion having magical use is of questionable value. In most cases, it seems like it would be better to 'grow your own channellers' using the dynasty system rather than impart some of your sovereigns essence on a champion. And in a real sense, a champion functions just fine without it. However, I will admit that if you can't get your dynasty started quickly enough, it's sometimes worth the cost to have another magic using champion.

Third, currently you can marry champions. However, if you are a male sovereign it is much harder to find a female champion than it is to find a male one. Also, it doesn't seem to make any difference in the game if your spouse is beautiful or ugly, strong or weak, a champion imbued with magic. Ideally at some point, the attributes of your spouse will make a difference, however, that's a topic for another time. Currently in the game, you do seem to need to hire the first opposite sex champion you find and marry them.

Forth, the final real advantage is that champions to lead armies, can go on quests, uncover special adventuring locations and use special equipment. Again, to use them in this capacity requires funding for equipment (and as creatures become more powerful, more expensive equipment). Your hope is that through experience and the purchased equipment, they become a force on the battlefield. However, often parties, squads or companies of normal soldiers are more effective at a much lower cost. If you invest your champion with magic and increase their essense at the cost of not increasing their normal attributes (like strength, health, combat speed) it can allow for some specialize attacks, but often the hero is then weak during physical confrontation.  

Fifth, there is also some real value in that champions have a 'profession' and can add some marginal value to your faction simply by parking them sans equipment in a city to add bonuses to your kingdom or empire. Again, in this case, hiring a 1st level hero gives the same benefit as spending more gildar for a higher level one. In this case, champions are worth their cost, but they are really more of a specialist not really a 'hero' in the sense of the word.

Summation:

Shop values for common equipment needs to be massively decreased, not increased. You should be able to outfit your champion in common equipment for not much (or any more) than it costs to outfit a single soldier. However, the shop should carry much more 'uncommon' equipment that is not available to the common soldier class.

Some NPCs should already be channellers and should cost more. Those that are, should be limited to one/two spell books so that you should hire ones that align to books that your Sovereign already knows (or you hope to acquire through research). This will add more interest to the game. If not magic, then give each a special attack or defensive feature much like what some monsters have.

Cost of higher level NPCs needs to come down by a significant amount AND they (all levels of champions) need to come equipped with better equipment making them worth the expense in gildar.

There needs to be an equal amount of male and female champions in the game.

Professional skills should increase over time. This makes the specialization a more valuable resource and consquently more valuable if traded to another faction during the game.

Champions should be potential difference makers in the game. Their initial cost should be an investment in that potential. I also believe that champions should require a on going wage much the same way as soldiers do.

Those are my thoughts on Champions.