You’re on to the issue and almost figured it out. Why are the tribes fighting in the first place? They have to be told that the other side is evil - either because they are attacking first or responding to it. Who is responsible for communicating that Truth and why are they doing it? The issue of weapons as a tool for cultivating traumatic experience does require this Truth. But the physics of the weapon are based in objective experience which is something else entirely.

"The other side is evil" is not a truth, it's a lie to deceive the dumb masses who swim in the sea of emotions and barely engage their minds. Truth doesnt change and is the same for everyone.