εὐεπιβουλευτοτέρας 8, 4, 3

he says that the left side was εὐεπιβουλευτοτέρας therefore he would seat there the most honored guest. I do not get it. would the guests attack each other when drunk or what?

Cyrus honored someone by putting him in a position from which he could easily be attacked from him. It was a sign of trust.