Treasures are classified according to their power or functionality by the Universal System.
1. Trash grade - basically junk but anyone can use it.
2. Common grade - minimum requirement to wield - D rank
3. Rare grade - minimum requirement- C rank
4. Epic grade - minimum requirement - B rank
5. Legendary grade - minimum requirement - A rank
6. Mythic grade - minimum requirement - S rank ( Demigod )
Though rare, some treasures allow even low ranked individuals to wield them.
Graham's Universal Gate is an Origin grade treasure - the only one in the entire universe.
There is an another grade that can't be classified properly.
Unique grade - anyone can wield them and the effect depends entirely on the user's level. Unique grade treasure's maximum power is just slightly below the mythic grade treasures.
There are still some grades I haven't mentioned for future reveal.😜