ok ok, in all seriousness, some of my power is a vague referance to either some chakra, or an occular technique, or some kind of other technique to help stop Sauske with. Imo there all valid guesses because, because we know Itachi can transfer techniques/occular abilites through touch.
But It was a shapeshifting immatation clone that touched naruto/ gave him "some power" and Kisames had only around 30% of his chakra. Could Itachis have had more maybe.
In the manga Itachis clone used like 3 juitsu(2 genjuitsu(one on naruto, one on Kakashi, and a Katon technique + the gift?) if he spread out the chakra evenly from those juitsu, that would be less than 10% of the clones/itachis chakra per juitsu and for Narutos "gift of power".