Warning: contains spoilers for My Hero Academia Chapter 315
Deku just proved in the latest chapter of My Hero Academia that he possesses a superpower far greater than One For All. It's not even one of the many quirks that he is receiving from his predecessors, either. It's his heroism that can sway the hearts of the most hardened villains.
For the last few chapters, Deku has been locked in a vicious dog fight against the hero traitor Lady Nagant, hired by All For One to bring the young student to him. She has proven herself quite capable in combat, as she's one of only a few people who can wield multiple quirks. But her capabilities are fueled by more than just her superpowers. Her resolve is hardened by her hatred for the hero society.
Lady Nagant's profound disgust for heroes stems from her own negative experiences when she served hero society as a public safety official. Basically, she was used to cover up the sins of her peers when they were so great they had the potential of destroying society's trust in heroes. Her role was to assassinate these heroes. She soon became so appalled by the hero's lack of transparency and utter disregard for justice that she later dedicated her life towards upending the entire system upon which these heroes existed and ruled society.
Yet, Deku's display of selflessness, bravery, and heroism is remarkable enough to actually make Lady Nagant consider changing her ways, all of which have been hardened by time and anger. He accomplishes this seemingly insurmountable feat by first putting his life on the line for Chisaki, the villain better known as Overhaul whom Deku once fought for torturing a young girl named Eri to rid the world of quirks. Deku then goes out of his way to save Lady Nagant herself, despite the fact that she has been hunting him for the last few chapters. Finally, he is able to see the good in her, regardless of all this. He points out that, when she ostensibly used Overhaul as bait to lure Deku over to him by firing a bullet at the villain, her trajectory had been off, and that she would have already defeated him if she were really on All For One's side.
It's remarkable that this works. Telling Lady Nagant that her hatred for society, upon which she had based all of her decisions and dedicated a good portion of her life towards destroying, either wasn't real or strong enough could have hardened her resolve or even given her enough fuel to overcome and kill Deku in anger. Yet, it ends up proving that Deku is able to connect and sway even the most hardened souls. Moreover, it's less likely that Lady Nagant's change of heart came as a result of her seeing the error of her ways, but that Deku had been not only willing but able to see the good in her. This is the act of a true hero, a state of being that Lady Nagant wanted so badly to exist within the hero society. Deku's true heroism in My Hero Academia is what allows her to see that there are real heroes and that the society she once trusted and devoted her life towards protecting can be fixed and become what she always knew it could be. This is a miracle that One For All could never achieve.