Suggestions for a SOD mod.

but this would have had to be done about 10 years ago, and today, even if such a mod were released, few people would play it, because everyone except beginners has become accustomed to a certain state of affairs over many years and simply won't use pointless skills.

Theoretically, this could be done step by step.
That is, implement one change and ask players to play with it, collect feedback, and decide whether to keep the change, adjust it, or remove it.

And this, to put it mildly, is a bad idea: to make an overpowered unit even more overpowered. No one would play "Heroes" like that.

In 1.5 years, I have rethought many things, and much of what was proposed is no longer relevant - for example, a separate school of magic, or moving the prayer skill.
And my vision of skills is completely different now.
But blindness in a two-hex radius seems like an interesting solution to me, especially at the expert level.