Quote Originally Posted by UChessmaster
I still don`t beleive that Kakashi deducted mang stresses itachi`s eyes because Kakashi himself has Mang., in fact even IF Kakashi has mang. it proves nothing, since Kakashi is not an actuall Uchiha the effects of a Normal sharingan makes him go uncounscious for a week after THREE techniques(see zabuza arc) , i supose if he uses something like mang he will be out for a month... that doesn`t mean itachi goes down after 3 tehcniques nor that he is down after 1 mang.

Again, if we decide that Kakashi knows about mang weak point because he has it himself, we`ll have to neglet some important parts of the whole discuccion, i emphasis again in the kisame flashback, what`s the point of it in the first place then?
He didn't need to deduce that fact by himself, he was there when Kisame told Itachi not to use it to much because it strains/weakens his eyes. He then states it again to Itachi, and Itachi praises him for that analysis with his same stoic, cold glare. But that's not the issue here, the issue is Kakashi's next statement of "Itachi, how bad has your eyesight become?" clearly induced a state of surprise and shock and that's evident by Itachi's statement of "Kakashi-san, you couldn't have..." and his facial expression and a slight gasp. Why do you think he had such a reaction? Because he was afraid Kakashi would find out that he had used it continuously and was possibly near blindness? No, I don't think he would have a reaction like that to something so trivial. Again, I point to Itachi's statement, people are denying the fact that this statement has A LOT of meaning.