I think my main problem with the Enies Lobby Arc was Kalifa. It was directly stated that she was the weakest of the group. She wasn't even a challenge for Sanji, who only lost due to his sense of chivalry. The weakest SH fighter, Nami, had to fight the weakest CP-9 fighter. Nami only has any fighting ability in the first place due to the special stick Usopp made for her. So while I do love Robin and Nami and think they are strong characters, there are still sexist elements in One Piece (as with most shonen manga).