So, according to you, classes focused on combat skills are ideal for a particular race?
Okay, let's evaluate (+ - suitable):
General - life (+, morale has always suited the light, death - +/-, suitable for a demon army, useless for an undead army)

Well, let's start with the basics. Any hero participating in battle will benefit from combat skills (so they don't get taken down by the first enemy). The question is when to take this additional skill.
The General's bonus affects not only monsters but also heroes, raising their morale, which allows them to act in time and cast spells.
I don't see any particularly useful bonuses (for Necropolis) in other classes besides the Fire Mage, so I won't touch them.
But for the Necromancer, the most useful skill is the 4th one, and if he doesn't survive, he will not only remain without experience but also leave the army without reinforcements. Therefore, it is quite natural for him to be able to withstand a random attack and, if necessary, escape from the enemy. In this regard, the Assassin is a quite suitable class. This is especially useful at the beginning of the game when there is no strong army to protect the hero.

Happy New Year!