Rather Mihawk's untouchable aura not be wasted on this washed up old legend.
If he fought Fuji, it would be much more badass. We know before Old Legends go out they are gonna be gassed at the expense of the character who will survive. Mihawk is supposed to be one of the unblemished top tiers, while I think he'd do better than most, I would still be worried for how Oda makes him look.
Though Kizaru was also one of those characters who had a somewhat untouchable aura, he had to be given depression for that to end, but Oda still refuses to draw Kizaru dirty or looking injured while Kaidou was coughing up liters of blood against weaker attacks. So it can be the same case with Mihawk, where he gets touched up only for him to be drawn relatively unharmed.