This Great Katana is the level 2 weapon upgrade for your Adventuring Fellow (NPC). If your NPC has reached Level 2 for weapon upgrade then you can trade this weapon to Luto in Upper Jueno
I made a good deal of money trading Nodachi from Norg to the Bastok AH. I was able to buy these swords for about 4700 and sell them at the Bastok AH for 8000. In Jeuno these went for 5500-6000, and in San and Windy they were very close to the Norg price, around 5000, sometimes lower as foreigners try to ditch their low level weapons for fast cash. I'm unsure why Bastok seems to pay a premium for low level weapons.
These will not sell turbo fast, but raking in 3k or 6k for just relisting Nodachi seems like a decent time investment.