User blog comment:B214/Shin DxD 1 discussion/@comment-175.138.188.184-20180926082732/@comment-28884330-20180927150126

Vali couldn't beat Crom, but he had the advantage in the fight, since Crom was by far the most injured one. And Issei has Ascalon and Ascalon II, which you ignored in your analysis. If anything, Issei has much higher chances of beating Crom than Vali, and Vali already fought equally with him. It's only logical that Issei has the overall advantage.

Uhh.... He didn't outlast Arthur easily. By the time Strada depleted Arthur's stamina, the game was already pretty much over. And Xenovia, unlike Arthur, doesn't have to use stamina in defense, which gives her an immense edge in lasting long against Strada.