Okay, so during Shachi vs Arima. Shachi comments as to how ridiculous Arima’s pacing is and figures out that something’s up with Arima’s eyes/eye (doesn’t specify if both or what).
He figures out that Arima’s weakness is his ‘blindspot’.
He tries to take advantage of this when attacking Arima and he thinks that he’s managed to ‘read’ Arima’s movements, but before anything, he gets stabbed right across his throat by Arima’s Quinque and gets electrocuted.
And Shachi falls to the ground.
Shachi: (Very impressive despite having ‘those eyes’…) Shachi: (Rize… You have to run away…)
This is just an assumption but the text in that page with Shachi says “読ん・・・” which is a part of ‘read’.
So I guess it did seem like Shachi had an advantage and was about to say “can read you like a book” or something along those lines but Arima… did that thing he always does.