Where Does Irelia's Control Of The Blades Come From?
So, from Irelia's lore, we know that Irelia was the daughter of the great Master Lito. With his art, a highly guarded secret, It was said that swords would "breathe in his grasp", and his teaching were sought by "ruling classes from nearly every city-state," until he died of a mysterious disease, leaving Irelia and her brother Zelos his weapon. Zelos became a sergeant in the Ionian military and was sent to seek aid from Demacia, which was when Noxian forces struck. Irelia, who was charged with the protection of their home, fought valiantly, but was cursed with Noxian sorcery, and was dying. Soraka attempts to keep her alive, and as she is on the brink of death, she rises and her weapon literally rises with her. From what was said about her father's art, Irelia had just learned what her father was famous for. From her judgement, we can assume that Master Lito was a true master of the senses, and discipline. From what Irelia said about how Lito would have never allowed her to hit him, we can assume that Master Lito was far more powerful than Irelia was at the time, and that they were not even close the the perfection that Lito supposedly had achieved. From what I can conceive, Lito was the strongest a normal human being could become.
Now, look at Irelia's title. Irelia is known as the will of blades. One would think that this would refer to her control over her blades, but perhaps it hints at more. Perhaps will is literally what Irelia's (and Lito's if he had that ability) derives her ability to "will" the blades to do as she wishes. Perhaps in the world of Runeterra, ones mind is a force, and when concentrated, as was by Irelia's when she was revived by Soraka, by will, it can become a potent force?