Legendary Urban Medical Sage

Chen Hao, orphaned at eight, had lost his parents and his inheritance to unscrupulous relatives. All he had left was ten acres of land. After returning home following high school, he was asked to provide his land as a temporary warehouse without compensation. Previously, villagers received a subsidy for this service, but this year, the rules had changed. The warehouse service remained, but there was no longer any fee involved.
With the financial incentive removed, no one was willing to offer their property for free. Eventually, someone suggested, "Isn't Chen Hao's house empty? Why don't we use his house as a temporary warehouse?" This idea gained traction among the villagers.
That’s how Chen Hao found himself surrounded by ten people, armed only with a rusty, ancient sword to defend himself. Faced with the fierce protests and threats from the villagers, he had no choice but to reluctantly surrender his warehouse. Now, all Chen Hao possessed was the rusty ancestral sword.
With no other options left, Chen Hao considered selling the sword. But just as he contemplated this decision, the seemingly ordinary rusty sword underwent a remarkable transformation. It suddenly began to shine brilliantly. Before Chen Hao could comprehend what was happening, the dazzling light overcame him, and he fell into unconsciousness.
What mysteries lie behind the seemingly ordinary rusty sword that left Chen Hao unconscious?