en_tn_condensed/jos/08/24.md

when Israel had finished killing all the inhabitants ... when all of them ... had fallen by the edge of the sword

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.

had fallen by the edge of the sword

"had died in battle" or "had died when the army of Israel attacked them"