Fifteen minutes ago, when Lin Mu had asked Duan Ke for a better quality weapons manual, she had actually not minded it. She would be open to selling him a higher quality manual if he was willing to pay the price for it.
But when Duan Ke felt her defensive spirit tool activate, she understood his underlying meaning. He did not just want a common weapons manual that's for body tempering realm experts, instead what he wanted was a weapons manual that's intended for a Qi refining realm cultivator.
Lin Mu's spirit sense had shocked Duan Ke, as she had never expected for him to become a cultivator this fast. It was only a month ago when he was in the 4th stage of the body tempering realm, and now he seemed to be a Qi refining realm cultivator. From what she observed, Duan Ke could tell that Lin Mu was at the 9th stage of the body tempering realm when he became a Qi refining realm expert.