User blog comment:B214/Question and Answers/@comment-5185939-20131008060026/@comment-9339850-20131008060645

that is if he is even able to convince strong enough people/beings to be his servants in the first place. Besides i dont think Issei's team is going to have servants that are that naturally strong.. more like Rias' peerage where they grow stronger by being with eachother and stuff