Don't despair Andy, specially if you didn't pay much for it
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You will end up learning something out of this; the world of Japanese swords is a vast universe, including superb examples that sell for many thousands of dollars, but that is not necessarily the issue here.
I notice that the peg ( mekugi ) that holds the handle to the tang hole is missing; check if there is a real tang with such hole ( not the continuation of an adapted broken blade ) and if it has the signature ( mark ) of the maker.
The handle is real ... a modest one, with the ray skin wraped by canvas strips and iron washers in between, instead of the traditional ornaments (menuki); such is a typical economic version, made in a hurry to equip the Tatsuma rebels, but still a legitimate one (see my example picture attached).
I also bought this in a junk condition, but the money i paid for it versus the opportunity to learn about this area, was well worth it.
If you are interested in developing your knowledge in these things, you may start by consulting Richard Stein's comprehensive web site, with a mirror in this Forum resource site
http://home.earthlink.net/~steinrl/nihonto.htm
Fernando