It should be relatively cheap and easy to send it to a university to check the origin by profile of the metals composition. If they really suspect it of being authentic the tests would have been done already.
I don't think that's ancient at all.
I wholeheartedly agree. In a later episode the bros take a trip to the lab where it was examined, and it was found to be modern. I suspect it's something like that. Probably some wall decor, or Masonic crap.