The eternal question: which heroes are better, mages or warriors?

We don't understand each other. Magic adds power to spells. Regarding necromancers, I meant the necromancy skill, which takes up 1 slot. And if you take all the skills you mentioned: leadership, ballista and catapult management, and diplomacy, as well as pathfinding, you will only have 3 slots left, and I listed possible options for further hero development.