Guaranteed:
1 - Shanks' Gryphon
2 - Garling's sword.
Guaranteed not to be Supreme Grade:
1 - Shiki's weapons
2 - Gaban's axes
Oda will not hand out two supreme grades to the same person, Zoro aside.
So, with Shanks and Garling guaranteed, we have 7 Supreme Grades in total.
We need to guess 5 more.
Possible wielders:
1 - Shamrock - considering his family wielding SGs, he could too but SG wielder getting clapped this early?
2 - Green Bull - relevant swordsman in final saga.
3 - Rocks - even alongside Roger and Garling, the biggest name of God Valley.
4 - Rayleigh - an old legend with unmatched aura. In case of more relevant swordsman in prime, Ray could drop out.
5 - Shiryu - The supreme janitor, self-explanatory.
Do you think Shiryu uses the same grade meito as Garp's peer Roger?
The man who ran through Roger's equal the Iron Garp is using a Supreme Grade? Hell yeah.
Roger is no longer a special benchmark, the man is inferior to EOS Sanjino.