Yea, its a little strange.  You can make a champion go down the administer trait line that gives some pretty nice bonuses for having them sit in a city.  BUT, the only way you can get them to have those traits is fighting in battles and not using those traits. Kind of a strange dynamic, at some point you have to decide that your administer is going to retire and sit in a city, but when?  Would be nice if those governor types could gain experience citing in cities too.

there is a building that gives a % chance that heroes stationed inside the city will gain experience.  I don't think that's a particularly good idea, but it does suggest it's theoretically possible to level up your hero without fighting

Hi this is indeed a problem and while this post is open, we could propose solutions. Here is my thinking. Heroes should be able to xp while doing other things : some should be able to lead caravans and do merchant missions (like send them in your own or foreign cities for a gain in gold and in xp), others be diplomats (improving relations with some cities, exchange research, make peace, gifts plotting and raising revolt risk), spies and assassins (check the city production, the troops there, sabotage production, poison the water, counter spying and of course, take out an enemy hero at night just before assaulting their city). These heroes could gain nice civic skills along each successful mission’s and gain xp but if they discovered or fail a mission snap, they die, return to a city (like any other hero) and get wounds and negative traits. It would also be another way to promote the intelligence attribute and make it essential for being a worthfull governor. While not doing a mission, these heroes could govern a city and give it great bonus (maybe some buildings like studies etc…could only give bonuses if an actual hero is attached to it). A lot of posts are touching outposts. On this I think you’re right, they need roads, to be garrisoned etc. Outpost should be like SoSE or Galciv, like military outposts (forteress), economic ones (trade post) etc..