In mentioning how they both have a 5 in databook, I in no way was trying to say they are equal in power regarding genjutsu. It's simply to show that Orochimaru too is very powerful with genjutsu in his own right.Agree and disagree. People saying oro's weakness is genjutsu clearly do not understand the manga.
Its already stated several times that the 2 vs 1 method is what is needed to fight a sharingan user because visual genjutsu are hard to combat and one's caught in them in a 1 vs 1 scenario you would lose.
Oro as you stated has a 5 in DB for genjutsu. To gain a 5 you need to be know in depth the category but also use it.
However note that just because oro also has a 5 doesn't mean that him and itachi stand equal in genjutsu, not at all. Merely means that oro is good enough to get a 5 just like itachi. It doesn't compare ninja's prowess and judge on this, but rather looks at the ninja as an individual. Not to forget that scores are capped at 5
The genjutsu oro faced was a kanashibari, or paralysis based genjutsu which takes away movement. Oro was struggling to move his arm in order to break free, but the reason he couldn't in time was because he was paralysed. Btw itachi NEVER came close to deal a vital blow. That genjutsu is close range to begin with, The proximity was always constant
btw the proximity wasn't constant. In that image, it is impossible for him to have been in that same location and cut Orochimaru's hand.