Chinese take the dragons as the supernatural creatures. The Dragon balls have magic power. It can improve the equipment`s quality while the equipment`s level will remain the same. For example, level-70 elite equipment may become level-70 super Equipment. The higher the level, the more difficult to upgrade the equipment`s quality. Once the improvement is unsuccessful, the equipment`s durability may go down while the equipment`s quality will remain the same.

How can I get the Dragon Balls?
You may get the Dragon Balls buying it from Shopping Mall, killing the monsters, completing some quests. Some fellow players may also sell some Dragon Balls.

Note: In the Shopping Mall, one Dragonball is equivalent to 215 CPs.

What are the Dragon Balls used for?
The Dragon Balls can be used to upgrade the equipment`s quality, socket the weapons, upgrade the weapons from level 120 to level 130, redistribute the attribute points.

More details here