He used it against kakashiYa it is true but Itachi was suffering from Illness, and to use water element+MS in a fight against Sasuke can consume a lot of chakra, and when he visited Konoha he was in far better condition, that's why..
That's what I am saying he was in better condition when he fought against Kakashi..He used it against kakashi
Tsukuyomi = child gloves?Itach didn't veiw Kakshi as much as a threat,because he wasn't uchia so he had child gloves on in their battle.