User blog comment:Piyush Banerjee/Shin DxD 2 discussion/@comment-2602:306:CD9A:C860:141A:858E:1B9B:BDB-20190201001403/@comment-10330822-20190201035352

The first was probably her and her peerage not taking the advice Issei was getting "don't let emotions get in the way". The issue with that fight is that a lot of people turned it into their own personal duel with Issei, namely Kiba and Issei. When logically, they should have made better use of their "pieces". Issei had a numbers advantage on Rias, and Rias took the initiative in the early game to get rid of that advantage by eliminating Roygun and Elmenhilde.

However, Rias didn't capitalize. Instead of grabbing on to her advantage and attacking as a group, she had her peerage seperate to try and lock Issei down. The problem was she seperated herself from Crom Cruach, and had Crom attack Asia/Fafnir instead of Issei, because apparently the other numbers of Rias' peerage were too involved with Asia to attack her. This is where emotions come into play, because logically Kiba should have attacked Asia, not Crom.

Instead Kiba fights Issei, partially because Kiba has always wanted to duel Issei, in other words, emotions. However, only Crom can be said to be stronger than Issei at this point, with Balor Rias and Prime Vasco being the next best thing.

So the struggle in this fight was between what Rias's teammates wanted and what they needed to do. Problem was, none of them were strong enough to actually achieve those desires.

Rias herself also wasn't as prepared as she claimed to be, and Issei eliminated her, completely eliminating the need to defeat Crom.