Yes, I would suggest that the Archer's knee was sliced off with one of those nasty new bronze swords that are present in the historical record - but it's only a guess. The most important bit of evidence was the charred grain allowing the dating of a Bluestone pit. The bluestone chips just indicate that these stones were the most reworked ones on-site. Which isn't unusual as they're also the oldest and, arguably, the most revered!