Mihawk vs xebec is irrelevant to the point.
1. Oda gave zoro santoryu to be the strongest swordsman ever
2. What xebec is doing this chapter will be a higher level of what Roger shanks do yet he is being outright hyped for this as a swordsman
Something
@ZenZu and others tried to argue excludes shanks from being one
This chapter outright ends any debate