User blog comment:B214/Volume 23 discussion blog/@comment-77.188.219.183-20170424155339/@comment-31137559-20170425044532

Vali still has his full DxD mode. While Issei's DxD mode had to be nerfed because Issei couldn't handle the power. And Issei and Vali can only maintain their forms for a short amount of time. But for all we know Vali could have mastered DxD or achieved a new form surpassing it.