Yubashiri was one of the 50 Ryou-Wazamono, the lowest class.
Perhaps Zoro will come across a sword from one of the higher classes in the coming chapters.
The way I thought it went was: Wadoichimonji - oowazamono; Sandai Kitetsu - ryouwazamono; Yubashiri - wazamono.
Ryouwazamono isn't the "lowest class" of katana at all by any means. It's just the lowest of the great katana, which are counted. It's like having an A- compared to an A or A+.
I believe that Yubashiri was actually in a class lower, as a wazamono, but was still a good sword. I really liked this sword, since the katana store owner bestowed the sword upon Zoro, hoping Zoro would take it to great heights as a swordsman.
As for the new katana, it would be awesome for Zoro to get a saijou-oowazamono, but it could seem a little weird with it being of "higher" rank than his main katana, the Wado. It'll be fun to see if he runs into Tashigi again though, when he's looking for the new sword.