So why Mihawk and shanks were duelling in the first place.
Why would wg send a Holyknight after Mihawk
For hunting Marines I guess.
Aside from that, maybe they met in Mary Geoise or they caught wind of each other's successes and notorieties and just happned to find one another conveniently or hunted each other down?
Its interesting Mihawk knew exactly where to find Shanks on that random unknown remote tropical island too. Vivre card maybe after they knew each other from before? Or he had some other way to find him? I have no idea how the hell Mihawk navigates the oceans with just his coffin boat but maybe he really does dominate and tame the ocean and weather with his aura/haki lmao.