User blog comment:B214/Shin DxD 1 discussion/@comment-95.210.189.106-20180809123512/@comment-28884330-20180809230834

Issei himself said Vali's DxD L was somewhat superior at the moment. Words in the series, no matter what you think those cannot be contradicted.

Also, Vidar with his armor was dominating Issei, and Issei only won due to having Ascalon and Ascalon II and using them strategically. Otherwise he would have lost.