Confirmed:
- [1] | St. Ethanbaron V. Nusjuro
- [2] | Gol D. Roger
- [3] | Edward Newgate
- [4] | Issho
- [5] | Dracule Mihawk
Likely:
- [6] | Harald
- [7] | Rocks D. Xebec
- [8] | St. Figarland Garling
- [9] | Shiryu
Maybe:
- [10] | Nika
Harald mentioned that Jarul gifted him his blade. Later, we learned that Jarul was the WSS of a previous era. It makes sense if Jarul had originally wielded a Supreme Grade blade.
Rocks's sword attacks were famous, and Roger, a Supreme Grade wielder, was his rival.
Among the Figarland Family, I think Garling, as the patriarch, should be the one to possess a Supreme Grade blade. Oda has already revealed Shanks's sword name but not its grade. Why hide the grade if most fans expect it to be one of the 12 best? It's probably a Great Grade blade. Shamrock's saber fittingly looks like a twin to Shanks's, so perhaps they're family heirlooms, which would make both Great Grades.
Shiryu treasures his sword and is a future opponent for Zoro.