Youtube video of the sword being unsheathed here. It looks like iron rather than bronze to me.
Part of me really wants to believe this, but a bigger part of me is extremely sceptical. Would knowledgeable Dopers care to chime in?
Quite a few links around, however you are right to be cautious, since there is apparently a market in copies.
It seems this sword is highly likely to be bronze - despite the colour but later era swords were steel
http://www.thehistoryblog.com/archives/45400
Don’t be too surprised at this state of preservation, there are better examples around
The article to which that post links doesn’t say whether the sword is bronze or iron, so I wonder how they make the determination? That sword sure looks like iron to me.
We have a spectral analyzer(cost=$25K US) which will tell you the composition of anything metal down to one hundredth of one percent.
I shoot ancient roman and Greek coins and get 0.03% gold, 75.22% copper, 24.55% zinc and 0.020% lead. Just an example.
China has entire museums filled with fakes.
A few years ago I went to a museum in Fuzhou and
“1000 year old” pottery and clothes looked brand new.
No deterioration at all.
That is so neat - I have some Roman coins my Grandmother took brasso and steel wool to sigh 
I probably should go online and try to ID them.
On my first reading I missed the “k”. I thought, twenty five bucks? I gotta get one of those.