I think there's another reason why the battle dragged long. Itachi might probably tried to make Sasuke out of chakra so that Orochimaru will show himself. I quite convince that Itachi was waiting for this and then use the jutsu to put Orochimaru in genjutsu forever. Then, Itachi's final wish is to pass all his tehnique to his younger brother so that Sasuke will be stronger to be able to protect himself 'cos Itachi will not longer be there to protect his younger brother. A lovely brother.....
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johntmh: Itachi