After characters reach level 60, players can do rebirth-related quests to become reborn. What are the benefits being reborn?

After the rebirth, characters will get an attribute stats bonus to increase the proficiency level of their skills.

After the rebirth, characters have exclusive access to the application of powerful gears. Players whose characters have not yet gone through rebirth can only look on in envy.

The character's level will be downgraded, but players can still any skills that were learned before being reborn and use any gears that they had before (after player met the requirement of the certain gears, again). All items in bags, warehouses, post offices and markets will also be saved.

So basically, characters are given a second life via the Rebirth system and will become much stronger.