User blog comment:B214/Volume 23 discussion blog/@comment-77.188.219.183-20170424155339/@comment-31137559-20170425121507

So you're basically saying that Apophis was far stronger than Azi Dahaka. And Issei can't use Ophis' power properly at the moment so it had to be nerfed. Issei received DxD through borrowing Ophis' power. Vali received DxD from Ophis blessing him. And that only reduced his lifespan because of the form's immense power. But Issei was actually using the power of Infinity that was within him.