User blog comment:Piyush Banerjee/Shin DxD 2 discussion/@comment-33939194-20181229062541/@comment-36523287-20181229072328

Indra gave Issei two pieces of advice.

1. Developing various ways to fight. Issei's main style is an unarmed combat focusing on head-on assaults. This style, however, is ill-suited against many types of opponents or situations. Thus, Issei need more fighting styles which help him adapt to any situations he may faces.

In both of his fight with Kiba and Rias, Issei has showed that he now has many ways to fight. When he fought Kiba. Issei combined swords into his fighting style, allowing him to block Kiba's dangerous swords instead of taking hits with his armor. And when he fought Rias, he didn't attack head-on as a usual. Instead, Issei observed, analyzed Rias's power and came with the most effcient method to defeat her. This is a great improvement from the power idiot he used to be.

2. Reduceing the dependence on Ravel when lead a team. Issei has relied too much on Ravel. If Ravel gets defeated in the middle of the match, his team might collapse.

It isn't necessary to have Ravel retire. Issei just needs to working harder as a king instead of leaving everything to Ravel.