Sorry if this has been already said but,
If you look at his dominant arm it's totally covered like he's hiding an injury. I wouldn't see a reason to hide it unless it actually was injured.
The fact that it's Sasuke's left arm and Naruto's right probably means they got that injury in a RvC clash. For that reason I think maybe Sasuke's headband is just there for show to fit his outfit better.
If you look at his dominant arm it's totally covered like he's hiding an injury. I wouldn't see a reason to hide it unless it actually was injured.
The fact that it's Sasuke's left arm and Naruto's right probably means they got that injury in a RvC clash. For that reason I think maybe Sasuke's headband is just there for show to fit his outfit better.