Show me where it was stated that the wound weakened Thor power level/durability. That's stupid to believe he was weakened when nothing suggests this. Superman/Surfer, and Black Adam all suffered injuries during combat and prevailed and still retained their power levels...that's what being a high Herald means.
He wasn't weakened. Thor best showings recently resorted with him still having this wound. Stunning Galactus, overpowering Surfer, and taking out Angrir. He did better with the wound than without. He wasn't weakened.
Let me break it down then: Thor was cut in the stomach by a coscmic parasite. That left him an unhealing, bleeding, painful wound. So much that his face would start contorting and he would start to sweat from the pain. What exactly is missing to make you believe that he was injured and weakened? A direct on panel statement? "Damn this unhealing bleeding wound in my stomach sure does weaken me"
it's not a regular wound and it wasn't intended to be a "shrug it off I'm Thor" wound either. Just let it go.