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It's enough to just discuss how to fix them.
Even the Governor – his maximum value is achieved when recruited on level 1. There's some value if recruited on level 2 (but it's rare). And on level 3, he's practically useless. Buff him, and he'll become a key factor in getting the desired skills. The same applies to other skills. Give the Artificer the ability to convert relics – he'll become a top priority in development. And if someone has to get it...
That's the problem with classes: they are very diverse. While in Heroes of Might and Magic, they try to do the opposite, reducing diversity and adding alternatives. For example, the Logistics skill – it's quite sad to play without it in Heroes of Might and Magic III, but in Heroes of Might and Magic V, there are alternatives like Speed and Explorer. And now, the Merchant will be added.
Therefore, the idea of shifting the functionality of classes to skills, while reducing their effect, aligns with the ideology of Heroes of Might and Magic V – the effect will be smaller, but more predictable.
For example, at level 20, they are practically equal: 100*1.6-30%=112, i.e., Crag is stronger in a direct battle, but in battles with monsters, defense feels more effective due to fewer losses.
And the fact that you don't use Crag or Gundula as heroes is your problem.
Also, Tazar has a more varied combat tactic. Crag practically always needs to move forward and attack, using tactics like mass haste/pre-cast spells, while Tazar can be used in a wider range of strategies, including ranged and magical strategies like "stand and shoot with archers/magic".
Also, Berserk – Crag will hurt himself, while Tazar is less affected by it.
And yes, against a map, Tazar's special ability is much more useful. That's why I say that Crag in the enemy's ranks doesn't scare me much. I would personally prefer someone like Moner in the enemy's ranks (say, for Castle), rather than Crag. And I would even consider switching to Tazar, even with such powerful heroes as Shahkti, Gosha, Tiras, Marik, etc.