Simple rule of martial arts mastery: Never teach any students.

Because you can bet your bottom dollar that one of them will turn out to be better than you. And that student will be the one to eventually fight you in an epic battle to the death.

At least it will be if your GM pays any attention whatsoever to how martial arts stories go.

Transcript

R2-D2: Wow, Ben. For someone who hates long, pointless flashbacks, you did a great job of hiding it.
Obi-Wan: Anakin, you've descended to the ultimate corruption.
Padmé: On the bright side, the only way to go from here is up.
Anakin: Yeah, so what? Deal with it.
Obi-Wan: That's precisely what I'm doing.
[SFX]: Whooom! {Obi-Wan attacks Anakin}
[SFX]: Kzrkzrkk!
Anakin: You saw my journey. You could have stopped me at any point. Why now?
Obi-Wan: You were my Padawan. I wanted to believe you would redeem yourself.
Obi-Wan: Now I see I was fooling myself. You've earned a failing grade in Jedi Ethics.
[SFX]: Whooom!
[SFX]: Whooom!
Anakin: That's it, Obi-Wan!
Anakin: You've failed me for the last time!