Going back a few moments before Matthew was finally able to change the flying aura blades trajectory mid-flight, his mind had already thought of one possible method that have a very high chance of working, and that was by using a similar principle that he had accidentally found back then when he experimented with his illusion element aura.
When Matthew was scouring his mind for a solution, the illusion aura experiment came to his mind and it gave him a solid idea about the technique that might work in being able to affect the flying aura blades that had already left his body. Although it didn't necessarily enable him to really control an aura that was already discharged from his body, it was still a method that made him able to control the aura remotely without having to have direct contact with his body.
