Posts from An example about morality and luck.
If we're talking about skills, it's not worth taking both; there are other, more useful ones.
And there's no point in checking the benefit; if Defense and Armor are positive, that's good; if Defense is negative, be prepared for an unexpected loss.

if the Battle Dice is negative, be prepared for an unexpected loss.
By the way, if the damage calculation formula is correct, then based on the attack/defense modifier for a strong unit (against a weak one), luck can add 25% damage, but in reverse – 333% (with weak base damage).
(Василь Симоненко. Люди – прекрасні)
You can't reason with stubborn fools!
Come on, how can you compare them? Both are good. Luck is just one extra move, allowing you to strike hard against someone else, while morale is like a double strike, a strengthened one. But the funniest thing is that both morale and luck can affect anyone and at any time...
I can add that in the case of morale, the additional strike can be directed at whoever you want, but in the case of luck, if the planned strike completely destroys an enemy slot, the luck bonus is wasted.
Справочник по НоММ-4 http://handbookhmm.ru/pamyatka-dlya-heroes-iv.html
Памятка по НоММ-3 http://handbookhmm.ru/pamyatka-dlya-homm-iii.html
и HotA http://handbookhmm.ru/vyishla-obnovlennaya-pamyatka-dlya-homm-iii-hota.html