Equipment with blue or higher quality have at least one additional attribute. The content and figure of the attribute vary. You can Refine the equipment to get your ideal attribute.
To refine equipment, go to Armory and click Refine, drag equipment to the box to start.
Refine costs gold or Refining Talisman. After refining, the stats of the equipment will be reset. Quality will not change. You can check the stats and refine again if you're not satisfied with what you've got. Meanwhile, you can lock an attribute which you want to retain. This will charge you some gold.