In Chinese, there is an expression "jeh do saht yan" ("borrow a knife/sabre to kill a person"). This expression means that one does not personally commit an act of homicide with one's own hands, but manipulates someone else into doing it for one. It's considered a very craven, evil thing to do.
Gu Long's Luk Siu Fung did not like to kill. Indeed, despite his excellent martial arts skills, he seldom used lethal force. When he anticipated more trouble than he could singlehandedly cope with, however, Luk Siu Fung often turned to his friend, the Sword God Sai Mun Chui Sheut, for help. The problem is that Sai Mun Chui Sheut knows nothing other than lethal means of resolving problems. To call Sai Mun Chui Sheut into action is to kill whomever you're sending him up against. In effect, then, when Luk Siu Fung asks Sai Mun Chui Sheut for help, is Luk guilty of "borrowing a sword to kill" others?