User blog comment:Blackendedsoul/Devil Fruit Limits and Physical Ability/@comment-4642018-20120125164915

maybe im repeating an answer... but this is what I think, you need to train to know how well to use it.. for example BlackBeard actually studied the fruit before eating eat, so he was well aware of what he was doing and capable of becoming with training. On the other hand, most Logia users think that there are invincible, but pekoms showed a logia not to get cocky just because he is a logia, because he lacks knowledge of his own ability or strenght, but pekoms trough good training his an amazing oponent.