Utilizing medicine is an indispensable method in knight training; without the aid of magic potions, it's very difficult to break the shackles of the human body and accommodate more Dou Qi to transform one's physique.
Scientifically utilizing medicine to achieve less than a tenth of the effect is already quite impressive.
"Even if Levis had not learned the science of medicine from me, he would have become a Sky Knight sooner or later. As the legitimate eldest son of the Tulip Family, it's impossible for him to remain at the Earth Knight stage all his life; as for Li Vera, it's hard to say. She still hasn't entered the elite stage, and the possibility of breaking through to Sky Knight seems rather small."
Knight training not only requires a great deal of resources but also a persistent heart.