Hello Matus,
I am new to Nihonto as well, I have a small collection of swords and growing collection of books. I have had the pleasure of using this site and the knowledge offered to keep me from waisting my money and time. I just bought a study piece for $200.00 from someone. I had looked at this piece quite a while back but decided to read alot more before buying it..
The blade was shortened, it had been sharpened by someone and part of it had been in a fire causing it to warp slightly to the right with some discoloration. It is a very old blade with a beautiful hamon and a fatal flaw which was the reasoning behind the shortening. My reason for writing this is because I didn't see some of this when I first saw the blade, but after reading and learning and actually putting may hands on varios blades, mainly through collectors with knowledge they jumped out at me.
Now to the money I spent for a study piece or should I say pieces, The tsuba is signed Efu Ju Masatoshi and the handle is a tightly wrapped wasp designed with beautiful menuki, appear to be ducks with gold bills and feet, on both sides. The blade has all the desire for study bad faults, bent, resharpened you name it but it was well worth the purchase if you look at the overall picture itself. I was taught to look at each part separate and judge it by that method.. Taking your time was the most important thing taught to me.
What I wrote may not help but listening to these guys will make the difference when it really counts, mainly in the pocket book and your collection will be just what you want.
Steve M.