The technique is a cultivation method that is considered to be a partial devilish art that dispels baleful Qi akin to methods from the Devil Dao by refining it for use later. It's refinement won't set one's path towards becoming an Elder Devil but shares similarities to the Devil Dao techniques.
Vajra Arts is a Buddhist body refinement cultivation art and it is very popular in the Spirit Realm. It's split up into seven layers.
This cultivation art can be used even by mortals without spiritual roots, but it's also renowned in the Spirit Realm for being extremely difficult to cultivate. There are very few people who can reach the third layer, let alone the fifth layer.
Most of the mortals in the Spirit Realm have only reached the first layer, which will somewhat enhance their bodies. Reaching the second layer of the cultivation art requires the cleansing of the marrow, which is an excruciating process that not many people can withstand. However, there are many mortals within the Spirit Realm and reaching the second layer would allow one to become as powerful as a low-grade demon beast. At the third layer they can combat low-grade cultivators and demon beasts. At third layer the transformation stature burst several inches in size, grew thicker, with four arms jutting out from his flesh. Fourth layer made users' body as hard as the average treasure, so they could combat a normal flying sword with their bare hands alone. If they can reach the fifth layer even mid-grade cultivators and demon beasts won't pose problems. According to Han Li, the seventh layer is capable of comparing to a Nascent Cultivator.
The difference between Brightjade Arts and Vajra Arts is that the former is cultivated using the spiritual power within one's body, while the latter is cultivated by forcibly injecting spiritual power from the outside world into one's body.
Vajra Arts in the Spirit Realm
Some exceptionally intellectually-endowed figures among the mortals in the Spirit Realm studied some basic cultivation arts used by cultivators and demon beasts, and managed to discover ways to refine their own bodies using the spiritual Qi from their environment without having to rely on spiritual roots. In the end, they managed to devise a unique set of cultivation principles, which became known as Vajra Arts.
Brightjade Arts in the Mortal Realm
In the Mortal Realm, the Brightjade Arts was found in the Feng Clan's secret cave of the Feng Clan's ancestor. It's a rare technique passed down from varja protectors of Buddhist sects. The technique is an altered version of the demon clan's technique and contains the missing portion from the Sacred Provenance Plate. It originates from the Elder Devil Realm.