[X] The Soul-Scarring Embrace, a spiritual venom which creates a traumatic vision and sears it into its victim's psyche, forever associating thoughts of violence and the martial arts with overwhelming dread and horror in their mind.
Personally I feel like the people saying we need to be able to dial-yield our crippling forbidden technique meant to rob a Martial Artist of their art are kind of missing the point, and might actually be the ones who start seeing our secret forbidden capstone power as something to solve all problems with, since its 'not as bad'.
Here's an idea. If someone's crimes don't seem that bad, we can just not horrifically traumatize or cripple them. Most practitioners you're likely to encounter are still baseline human enough that after being beaten to unconciousness you can chain them up and they'll lose most of their threat. Only people of Shaw-level or greater could maybe be expected to still win a fight while their feet and hands are chained, and probably not against more than one or two people.
There is usually the option of just throwing people in jail, assuming the place has one.