This story is about a main character who is a wind mage. He's not talented enough compared to other mages. When he's older, he creates/finds time magic and is then reincarnated. He was one of heroes party who killed the Demon King, and he had a dark elf/elf student.
Could this be The Mage Will Master Magic Efficiently in his Second Life...?
Zeff Einstein spent his whole life mastering red magic and was finally recognized for it, yet a new spell that was soon created revealed that his talent for red magic was his lowest. Bitter at the thought of all his wasted effort, he creates a spell to send his old self back in time to his younger body and together with the determined "genius" mage Milly and the handsome swordswoman Claude, he intends to master magic more efficiently this time.
The plot is very similar to what you've described, except that the main character, Zeff Einstein, specialises in "red magic", which appears to be a form of flame magic rather than wind magic, although in black & white, it looks like he's projecting gusts of wind.
The story takes place in a world where there are different forms of magic, which are classified by different colours, and individually graded. At the beginning of the story, Zeff is a middle-aged man who was regarded as the supreme red mage in his kingdom.
However, a means of determining a mage's maximum potential in each form of magic is discovered, and it turns out that although Zeff has maxed out his potential in red magic, his full potential in it was lower than his full potential in every other form of magic. To make things worse, it's been established that there's a boy who's potential in red magic is higher than his. As a consequence, Zeff is stripped of his title of "Flame of Flames" and cast out in disgrace.
Zeff then uses a "time leap" spell to transport his consciousness back into the body of his much younger self, so he can relive his life and master all forms of magic, rather than specialising in red magic like he did before.
Could this be The Unsuccessful Yet Academically Unparalleled Sage ~A Cheating S-Rank Sorcerer's Post-Rebirth Adventurer Log~, also the answer to this question.
The main character was considered one of the most powerful magic users in the country. Together with three of the other most powerful magic users, they defeated the demon king. He found a dying demon who asked him to save her child. He took that demon's child as a student, her appearance is that of an elf. One of the other powerful mages creates a test to determine compatibility with types of magic where you put some hair in some magic water. The main character then found out he had no compatibility with any of the elements.
After reincarnating, we learn that his student was the demon king's daughter, and is now the headmaster of a magic academy.
A couple possible complications:
- the main character uses lightning/thunder magic instead of wind
- the main character has a reincarnation skill, rather than learning time magic