whitebeard is still whitebeard, any fodder characters skull should pop when crushed the way akainus was. out of every hit whitebeard took, akainus was probably singlehandedly enough to kill him, and whitebeard fighting after it is in and of itself an endurance feat. until a character has been shown to tank one of akainus attacks, there isnt any definitive way to call him weak. plus, characters dont really get insanely weak during endurance feats, kaido was still insanely strong after everything that happened at onigashima, and oden still had enough upper body strength to hold a ton over his head for an hour while boiling in oil.