levels

level 0 = children, old people and normal weak people

level 1 = normal adult male strength

level 2 = strength of a well-trained common soldier

level 3 = strength of a veteran soldier

level 4 = elite of any army, usually commanders

level 5 = level of a common golden guard

level 6 = peak human, example = Arthur Dayne, Oberyn Martell

level 7 = freaks that surpassed humanity, example = Gregor Clegane zombie

level 8 = mythological beings

Although level is important, it doesn't mean that a higher level will always defeat a lower one, for example although Arthur Dayne is only a level 6, most likely he would defeat Gregor Clegane zombie, after all his sword skill is the strongest

The level is basically physical power, agility or intelligence, if any of these 3 attributes is strong it will level up, so the level is not just for strength, a soldier with good sword skill can beat someone with no higher level skill

the level is just something i put in to have some standard of strength, it's not something absolute