Originally Posted by Konnaha_yellow_flash
Itachis sasanoo is supped up with three spiritual equitments.
1. The Sword of Totsuka the seals away the enemy in a drunken genjutsu forever.
2. The Yata Mirror that can deflect ANY attack!
3. The Yashi Magnatama that allows itachi to through huge tomoe shurikan and maybe even something else.
IMO, by first having to complete his sasanoo then go around, find and add these equipments itachi over used his sasanoo which is why he was spiting up blood and acting weak just as sasuke did.
I remember reading somewhere that these were the names of some buddhist religious treasures, along with susanoo, and that because of this supposedly every susanoo uses these legendary weapons. Though I can't recall where at the moment.