The 'World' power system will be based on levels, and at every certain level, there is a corresponding title. Below will be the titles.
Lvl 1-10 > None
Lvl 11-20 > Copper
Lvl 21-30 > Iron
Lvl 31-40 > Silver
Lvl 41-50 > Gold
Lvl 51-60 > Platinum
Lvl 61-70 > Mythril
Lvl 71-80 > Orichalcum
Lvl 81-90 > Adamantine
Lvl 91-100 > Royal
The rankings of items will be also based on the titles only not the levels. And in every title, there are three sub-grade; inferior, intermediate, and superior.
For example, A sword that is an inferior Silver rank is stronger than a superior Iron rank sword.