Ideas and suggestions.

I had an idea, although it might have already been implemented in Heroes 5. Introduce a building called a "Mentor." Allow players to reset a hero's skills for a fee. If the topic of rebuilding the guild has already been raised, why not also rebuild the hero's skill tree and reset unwanted skills.

In Heroes 5, there isn't as much variety in possible heroes as in Heroes 3 (using a hero who isn't native to the faction is usually very disadvantageous for several reasons; there are only 8 native heroes). And it's impossible to quickly train a new hero (there are no treasure chests, and an army on a level 0 hero cannot fight effectively against strong guards). Nevertheless, mentoring is very limited in terms of gameplay experience on tournament maps (the chance of generating a mentor exists only in treasure chests, of which there are usually only 2 on the map, and the number of resets is no more than 5 the first time and no more than one thereafter). Introducing it in Heroes of Might and Magic VII would make the game less diverse – everyone would play with a very limited pool of heroes.