It was not a secret in the Capital that Yu Wan knew medicine. Back then, when the State Preceptor of Nanzhao came to visit, she was the one who saved Wan Feng when he fell and was injured. The imperial physician even praised her for her brilliant medical skills and good treatment. Yu Wan could understand if he asked her for treatment, but wasn't Han Jingshu poisoned?
Outsiders did not know, but as an internal minister, how could Jun Chang'an not know the truth? The imperial physicians of the Great Zhou were not so lousy that they could not differentiate between Gu and poison, right?
Actually, at that time, the matter in Nanzhao had caused a huge commotion. Many citizens in the Capital knew that the holy artifact of Nanzhao was in her hands.