Because Yoru is such a unique sword, Mihawk has a lot of weird grip styles. He uses the crossbar for extra leverage sometimes, and itโs almost like he swings it from the crossguard more than he swings it from the grip, if that makes sense. Because itโs such a unique sword, he must have come up with all of these moves on his own or learned them from Yoruโs previous owner. He also knows how to use its weight to his advantage.
Like putting his back hand on the crossguard so that he can bring it around faster like this:
But he hardly ever uses a normal grip. His hands are always positioned for maximum control and power, but it depends on the situation.
Watch Mihawkโs grip on Yoru as he completes his strike on Zoro. Also note that in the anime, he finishes with the blade side up, but in the manga the blade is pointed down.
If you try to recreate his strike keeping your hands like he did, you'll see it's impossible without switching your grip.
This couldโve all been avoided if Mihawk had used a baseball swing, crossing from one shoulder to the other.
But in order for the sword to end up lower than his waist AND pointed behind him, either he has 360ยฐ wrists or he had to switch his grip at some point. He literally
only did this for dramatic flair.
Maybe Oda just drew the starting pose and the ending pose without thinking about it, or maybe he means to imply that Mihawk is showing off by switching his grip at the last second so that his finishing pose looks cooler.