LIFE'S LOSERS NEVER LEARN FROM THE ERROR OF THEIR WAYS.
Personally, being This old of a blade, I would have it restored. But it will be Costly, to say the least. Putting a correct Polish on a blade used to be in the order of $100 per Inch. I have no idea what it would cost today. But, if professionally restored, you are looking at a decent sword worth decent money as well. Whatever you do, do Not attempt any repair or polishing on your own. It is Imperative that it Must be done by a specialized Professional who deals Only in Japanese swords, or else it will be permanently ruined and made worthless forever.
"Much that once was, is lost. For none now live who remember it."
My greatest fear is that one day I will die and my wife will sell my guns for what I told her I paid for them
"Don't tell me these are investments if you never intend to sell anything" (Quote: Wife)
Hmmmm .... I missed this one -- I was in Japan when it originally posted.
(Chrysanthemum Mark) Izumi [no] Kami Kanesada
[EDIT: I see that Bob Coleman gave the correct answer already.]
Thanks Bob and Guy, the rust scares me, should I buy or let it go???