This is an incredibly silly thing to say. If someone makes a knife that is terrible at carving wood or cutting food but is the perfect shape for, say, clitorectomies... then maybe that tool is bad and we should probably stop making it.
Yes, people choose to make it and people choose to use it. But, like... stop those people, right?
Morality requires agency and conscious agreement. A machine/device doesn't choose to be made or operated nor can it act against its maker/operator any more than rocks can act against the Earth. Regardless of motive, a moral conclusion can't be reached about the object.
This hypothetical knife that you've invented still doesn't make any choices. A person still makes the choice of how and when to use it. That's all that matters. Only things that can choose to act can be judged as ethical or unethical.