Aha, another Jackal story!
I liked this overall; it was a good buildup, like watching a storm about to break. I appreciate not knowing what the results of the narrator's return will be (even though they're perfectly convinced of what will happen!), although I would have appreciated a little more information on what is likely to occur (at the same time, the story is 1st-person limited and the narrator is telling us everything they could reasonably know at that point in time).
I think this was a good use of the 'unconventional weapon' idea - a weapon powerful enough to change a society's way of life has to be pretty "unconventional" - but here I would definitely have preferred an idea of what exactly the weapon might be. Not exact technical specifications, but a hint or allusion as to its nature or powers or capabilities; all I know is that it's large enough an adult Jackal has to drag it rather than carry it. Is it "just" a weapon? Is it psychic or even daemonic in nature? What can it do - destroy cities, control minds, raise the dead? What? A hint or two would both make the story more satisfying, and actually help the rising tension you were going for, as I could better picture what was about to happen when the narrator reaches their destination.
In any case, a good story overall, and a nice piece of writing!