I ended up passing on it... The patina (in the form of mineral acretions) was nowhere near what one would expect from a bronze item of antiquity. Nonetheless, it was beautiful, and I gave it some more thought, but passed in the end. They did have plenty of legitimate antique pieces, but I really doubt this sword was one of them. I found some close-up photos of legitimate Bronze Age swords from both China and Luristan to show the owner (who didn't speak English), so I could show him the difference. Nonetheless, it was a beautiful and well-made bronze jian with exquisite detail to the hilt. When I get home, I'll move the pics I took from my phone to my computer and post them to this thread.
Once you know what to look for, it is relatively easy to identify natural mineral accretions. The problem is, not all (old) bronze will have them...
Anyway, thank you for chiming in, and at the end of the day, I'm happy to say I saved my money.
