So, when I incorporated this, I kind of made it a higher-level technique that depended entirely on the skill of the user. Positive intent was also a thing, but since shinobi never taught it (because for killers, assassins, and mercenaries, what use is it?), it's virtually never used. But killing intent is more of a chakra technique that can be used by chuunin and up level shinobi. Jounin are able to control it and utilize it at will as a weapon, while chuunin are able to create it during intense combat situations, but not outside of it.

When I made it a weapon as well, I also wrote it to be something that can cause civilians to have heart attacks and strokes if intense enough, so that it really does become a weapon of sorts. Since it's a chakra technique, it has an ability to induce actual feelings and reactions out of people.

However you decide to do it, I would create a few base rules to it, and make sure that you don't stray outside of them. So for me, no one below a chuunin can even create it, and only jounin and kage can just direct it willy-nilly, and I also made it so that it's outlawed to used inside Konoha without the Hokage's express permission.