Ultrasonic vibrations have been successfully used to make cutting tools more effective for a long time. It doesn’t make the cutting edge sharper or amplify the force, it just moves it back and forth slightly, in microscopic imitations of a cutting motion. That does work. Though at the end of the day it won’t magically make a dull knife sharp.
Ultrasonic vibrations have also been successfully used to get shit off of surfaces for a long time too. It is a common and effective method. Though it usually involves a bit more than just shaking the thing, but still…
Theoretically this knife could very well do both of those things. Probably not well enough to be worth 425 dollars, but probably entire useless either.




As far as I know it’s dangerous play, because you’d be making it impossible for anyone to challenge the ball without things getting dangerous. You’re supposed to defend the ball by using your athleticism to fend off your opponents, not by using medieval battlefield tactics to force a siege.