In Karate Kid the mantra of the Cobra Kai Dojo is:
We do not teach anyone to be merciful here. Mercy is for the weak. An enemy faces you he deserves no mercy.
Within those 3 lines, it says we don't teach mercy, be merciful to the weak, and enemies get no mercy.
Did the bullies actually ignore the teacher invalidating what is said later about no bad student, only bad teacher?