Hi, i forgot about a title of CN novel. The MC was dying on early chap, and soon awaken as his young self with all his old knowledge in keep. he life on some sect, with his other 2 brother and 1 master, soon he killed one of his brother because he know he is shit. and on early chap his other brother found some fish that can be used as cultivation material and the mc told him to keep it safe (not to eat it). after that he become one of secret agent that his sect sent to some town (palace) to keep the young highest (the prince is a woman who hide her identity as a man) save, and the mc become some tyrant who punish all spy on the palace and make the palace clean. the mc isnt very strong (if im not wrong i already read until ch 170) but he using all his history knowledge to turn back the table. his loved one got injured in early days (when they meet on his 2nd life, her guardian almost dying and was trying to find a good doctor to save her) and he made her a really good sword or saber (i forgot) that can cut others sword easly later. all of his friend was someone who is GREat at his past life and he trick them with a cunning style. please help me, thank you