User blog comment:Piyush Banerjee/Shin DxD 2 discussion/@comment-2602:306:CD9A:C860:A9B0:D607:7141:9234-20190706015400/@comment-28884330-20190706175059

Vali's battle experience is meaningless as Issei has constantly fought competently and even won against people with comparable battle experience (Cao Cao, Dulio) or with battle experience that's much superior (Euclid, Vidar). His advantage in magic is irrelevant because even if Vali could seal Gasper's eyes one time, he didn't use anything other than blasts when fighting Strada and Crom Cruach, which indicates he cannot use actual weird and useful magic at such a level of strength. He's on Issei's standing there going by factual analysis.

Infinity Blaster and Compression Divider, first of all, are not the same type or even tier of attack, so comparing them is imprecise at best and meaningless at worst. Let alone the fact that Vali hasn't shown the ability to use Satan Compression Divider consecutively, it turns out that Issei can still fight after using Infinity Blaster. When fighting Vidar, he could fire Longinus Smasher, use Transfer and Penetrate on Ascalon, throw it with great accuracy, and then do the same with Ascalon II. All after using Infinity Blaster. That's a pretty ample range of action.

Vali has superior speed to Issei but it's not such an immense difference as what you're implying. They're still in the same power class (Heavenly Dragon-class) so regardless of what difference in specs each one has, they're still in a range that's comparable. If Vali avoids Issei's Dragon Slayer's, it would not be "easy" at all. You're also forgetting that not only has Issei fought opponents faster than him and hit them with his Dragon Slayers (Vidar), but also that he can use his Dragon Slayers' power on his blasts.

Vali has advantages in this fight, but they aren't nearly as substantial as Issei's. Issei has the highest chances definitely.