The ship I needed was in the desert, and some “adventuring” needed to be done to reach it and get it afloat. This involved using a skull to find a bell in some quicksand, and then having the bell polished. Obviously.
That complete, and it was into Dungeon 7. Have obtained the map and compass here, and I suspect the weapon may be some kind of grappling hook or possibly a more powerful bomb. Or a chicken.