Which fight did you guys considered the hardest/more challenging? In honour mode.
In Honor Mode? Probably...
- the Raphael fight (the risk of being nuked into oblivion if something goes wrong is pretty high and you are constantly conflicted between focusing the pillars to debuff him and nuking the adds to remove a nagging thereat)
- getting the Iron Throne right in a single attempt (having a clear plan about who needs to go where and when it's definitely time to rush back)
...are the two most challenging parts in the entire playthrough.
I had virtually no trouble with Sarevok, to the point I find it a bit underwhelming, so it's weird to see it mentioned as a difficulty peak.