Wei Wuxian's true abilities, it can be argued, lay not in his original talents as a cultivator but as his improvisational ability to invent and adapt.

He invented:

Paper Metamorphosis: a dark arts technique where a person places their soul in a piece of paper to spy but any damage done to the paper damages the person’s original body. The paper body is also fragile and cannot attack or move heavy objects. There is also a time limit on said body. Wei Wuxian used this technique in chapter 47

Empathy: He was the one to develop the technique Empathy which allows him to view the memories of fierce corpses. This includes A-Qing, Nie Mingjue and AnXin.

Intelligence: Wei Wuxian is by far one of the most intelligent characters of the series. He used deductive reasoning to figure out it was not a spirit eating monster that was stealing people’s souls but the demon goddess statue. Similarly he was able to see through Xue Yang’s disguise as Xiao Xingchen, A-Qing’s true intentions in helping others, Jin Guangyao’s plans in murdering the other cultivation sects after his secrets were exposed, and that Nie Huaisang played a major role in manipulating the events that would reveal Jin Guangyao’s true nature.

Charisma: He has demonstrated the ability to quickly charm and befriend those around him even though his talkative and mischievous nature gets on the nerves of others.

Leadership: he has shown terrific leadership skills in caring for the junior disciples.

Swordsmanship: he demonstrated excellent swordsmanship in his use but does not seem to use swords anymore due to lack of practice.