Heroes 3.14

-3 morale for Ballistics (-2 is already quite strong at Expert level, and you can stop there). Mana amulets have the same value and should restore the same percentage of mana; Armageddon does not require enhancement.

That's reasonable! Regarding fire, there's an alternative suggestion – again, borrow from Might and Magic V: Fire Strike reduces 50% of defense for 1 turn.

I would add +1 to attack/defense/strength or knowledge for every 5 levels to the Learning skill.
And the Legion artifacts seem a bit too overpowered.

- again, you can take it from Might and Magic V: the Education skill gives an additional +1 to the main characteristics for every 4th (3rd, 2nd) level.
- so you found the Head, brought it home with a chain, and got +3 horses next week (and there's still a loser in the city) – would you trade all this for a +5 club?

Was the infinite number of Pi chosen for a reason?

Yeah – the idea is to refine everything further without breaking the core mechanics.)

This might only seem interesting to someone who hasn't played War of the Triangle.

As far as I know, War of the Triangle has far more fixes than HotA; it's not "Heroes of Might and Magic 3.1..." but already a separate game: experience for stacks of monsters, daily salary for troops, etc.
The balance of skills is also overloaded. Take Ballistics and Artillery:
Artillery gives +5/10/15% to ranged attacks; at Expert level, you can buy a war machine, and artillery specialists also receive an additional 5% for each level to the percentage increase in ranged attacks.
Ballistics gives +1/2/4 cells for shooting without penalties; at Expert level, penalties for shooting through walls are also ignored.