Mental strength isn't needed in a fight; otherwise, boxing weight classes would be divided by IQ level. An Orc is simply twice as heavy as a female Orc, and it would be a disgrace for him to be weaker. But he is indeed weaker as a fighter (even if you take away all the spells and debuffs from the shamans).
If you consider everything from a physics perspective, then everything is as you say, but we are talking about the world of swords and magic. This is a fantasy world, and it doesn't only obey the laws of physics; magical abilities often outweigh the physical characteristics of the opponent.
[Модификация]Phoenix Vision - Комплексное модифицирование визуального аспекта игры.
[Модификация]UNIT-Баланс существ + визуальные изменения.
[Модификация]NewTransformUndead-Таблица поднятия нежити.
[Модификация]VisualFix-Устрание визуальных багов.
Карты для Heroes V 3.1:
[Карта][1x1]The Last Stand - Дуэльная карта финальных битв
Группа VK:
https://vk.com/club176978884