@Hexi Yes yes we can say that but tang clan is really strict in this. They think that if women try to learn about this poison skills or dagger skills they'll spread this to other clans where they'll be married. Thus, there all secrets would be out and people will make antitode for each every poison they have and also take out disadvantages of their dagger skills. That is the reason they don't want them to learn.
Spoiler!
But it will be another matter in the future though likely after 1400ish chapter I don't remember the ch no. Tang clan agrees to teach their daughters the techniques but only when they decide to not marry anyone and stay in the tang family.
Have never been this thrilled....