The writer uses both of these sentences, which mean almost the same thing, to strongly say that the Israelites had obeyed God's command to kill everyone in Ai. (See: [[rc://en/ta/man/translate/figs-parallelism]])
Here "fallen" is a euphemism for dying. Also, "the edge of the sword" represents whole swords, and swords represent either battle or the army of Israel. AT: "had died in battle" or "had died when the army of Israel attacked them" (See: [[rc://en/ta/man/translate/figs-euphemism]] and [[rc://en/ta/man/translate/figs-metaphor]])