I'm guessing it's a "they forgot" thing, since usually in cases where it's a stylistic choice to show the character's expression or something, they at least draw like, the outline of the eyepatch (or whatever's blocking the expression) but just don't fill it in, but here it's completely missing.Weird how he's wearing the eyepatch at the beginning, then doesn't wear it in some panels and afterwards wears it again at the end. I wonder if the mangaka simply forgot to put it on him for those few panels or if it's a stylistic choice.
Akchually...pirates and buccaneers wear eyepathes when fighting bellow deck when boarding ships! It allowed them to see better in dark quarters, it just need some get used to a vision without depthEhhh but wearing an eyepatch would make him worse in combat, your PoV is worse and your essentially blind to one sides attacks takes time to adjust.
I feel like he could have done alot of this pre-trap point too, sure they are more tired now and reduced numbers but he's insanely over leveled compared to all of them.