im not sure about the context surrounding ippo's weakness. at first i wanted to brush it off, but comments made by takamaru, his mother and mashiba, coupled with the loss to sendo, has made that impossible. By ippo's own admission he has never known what it means to be strong and now other people are starting to realize what he has always known. Which is actually good news, because for the first time ever he might be able to take a step toward his goal of being strong. His support system, childhood, and natural talents have allowed him to be successful without becoming stronger as a man. His mother doesnt notice any changes in him, because he has always been a strong and determined boy. She knows he isnt a man yet, and so does kumi, and mashiba, and takamaru, and the old man. Sendo, while not as talented as ippo, has the will of a champion, which is why he is stronger right now. His whole deal was being physically stronger than everyone one he fought, despite being physically weak in the big picture, losing to ippo he realized he had to train harder and become physically stronger. Mentally he has always been like takamaru, in that he believes he's the best and is always ready to fight to the end. Physically ippo has always been strong, and is constantly getting stronger, but mentally he is nothing like takamaru.