What is item might and resistance in unit attributes?

I do not know if it adds damage, & resistance, but I do know that Might, & resistance applies to troops only... not the hero units. Tactical Might, & Tactical resistance applies to Hero units only, not regular troops..This is not found in the game anywhere. No mention of it anywhere in game. They put all kinds of stuff in game with no explanation whatsoever, & just expect you to know.