Cool story. I liked it, and the visual of the skullbone with an arrowhead in it was welcome, as well as sufficiently out of context not to feel gruesome.
I think the headline of "Europe's Oldest Battlefield" is more likely to be accurate than the article's "world’s oldest battlefield," but there may be some nuance of meaning (oldest with war dead actually found in situ?) I'm missing. Neat thing to learn about either way.
The iamverysmart contingent that refuses to read the entire articles is out in full force in the Gizmodo comments, with several people suggesting that the foreign arrow heads were from trade ("The foreign arrowheads have not been found in tombs in the Tollense area, indicating that the arrowheads from elsewhere didn’t simply make their way to the region through trade."), and several others musing on what the metal arrowheads might have been made of ("The arrowheads were flint and bronze.").