There are no tacit accessories in the big talk. How can I refine it to level 4?

Equipment with tacit understanding can be cultivated and can be born to level 6; Equipment without tacit understanding can only be made and upgraded to level 3. There is no tacit understanding in the world to upgrade to level 4 equipment, which is given when doing tasks, and keel is issued when you want to do tasks. Like Jiuzhuan, some of them were bought with the serial number # 109 issued by the new customer system.