What's this mean??

[jordan]

So a friend just brought me this tanto blade with this tsuba I'm just trying to figure out what this means and what it's from and what it might be worth

[Ray Singer]

The blade is signed Naminohira Yasutsune.

The tsuba looks like a modern, decorative replica.

[ChrisW]

Nakago looks way too long for a tanto.

 

The bohi is running through the boshi which suggests that this is the bottom half of a broken blade. And lastly, with the scrubbed nakago, there isn't much left of this piece. And as Ray points out with the tsuba, this makes me feel that there isn't much of value here in my eyes.

Sorry to be the bearer of bad news.

[tbonesullivan]

Definitely looks like it was once much longer, broke, and then was used quite a bit, or just got rusty and was cleaned a bunch of times. It has led a hard life, and probably best left as is, as that is part of its history.

[GeorgeLuucas]

It looks like someone took a likely broken sword, and turned it into a "bowie knife", by grinding a new tip and clip-point. 

I've seen a few nihonto modified in similar ways. Definitely not original, and probably done more recently and outside of Japan. 

I agree with what's been said above. 
Best of luck,
-Sam