Why are you saying it like itachi was the character that kishi NEVER gave him some special powers or abilities..
Oro for example, Kishi ignored him in shippuden, DIDN'T get any power ups of any sort, he lost his arms, and even when he got hashi's DNA and got his arms again...kishi ignored him again as it's like he is a side character..
Itachi never lost in a battle..Was talented...and got many abilities...yet your saying, it's unfair "itachi never got power up"
Lol..does he even need one..kishi always made itachi brings some random jutsone ofut of nowhere just to make him win and for the plot..used totsuka and yata in Sasuke's fight..without even mentioning it before...then izanami in kabuto's fight....kishi just doesn't have to give him a real power up...you know it's like itachi is getting power ups indirectly.