User blog comment:Piyush Banerjee/Shin DxD 2 discussion/@comment-207.242.44.6-20181218202559/@comment-29963364-20181218221531

The passage goes...

"Issei and the girl were interrupted by a group of unidentified devils and he decided to fight the mysterious devils in his crimson armor and overwhelm them, causing them to tremble in fear . Issei asked Ddraig about his current strength which he says about on the level of a Satan-class and  wearing his crimson armor would put him on par with a Super Devil ."

Ddraig says that Issei in his "Crimson Armor" (Cardinal Crimson Promotion) is on the same level as Super Devils. This would mean that Issei's strength in normal [Balance Breaker] or [Illegal Move Triainna] is now Satan-class.

However, this isn't to say that Issei is as strong as Sirzechs or Ajuka. It's most likely that Issei is around "Rizevim level" or higher.