I don't think Vitali displayed an obvious weakness stylistically or otherwise in any fight to be honest. If there was a weakness he kept it well hidden.
He was not dominating Byrd, but he was winning decisively on the cards. Most rounds were close and he only outlanded Byrd by 8 punches for the entire fight.
Vitali doesn't really have a glaring weak spot in his game. I would say he gets schooled by certain ATG fighters(prime Ali for one), but that's more about how good those fighters are rather than Vitali lacking anything.
vitali's weakness is his boring robotic personality and boxing style/lack of heart. he is the tin man of boxing.
Equating chess with fighting; "Everyone plays chess but nobody is an expert. Everyone is an expert but nobody fights."-Vitaly klitschko
Vitali fought clearly with two arms all night. You like to think that and make excuses because Vitali could stop him after recieving a slap around the face. You k2 fans are a joke.