User blog comment:Gilgamesh79/Demonic Energy and Magical Energy/@comment-82.178.102.63-20170829160229/@comment-31137559-20170831122853

Issei had boosted the demonic power she was able to use and release in Volume 3 through transfer. You might say that she increased her demonic power since then. But did she? Or did she just develop the demonic powers she already had? Rias is still young and needs time to develop her demonic power and use it. That means increasing the demonic power she's able to release at one time and get used to using it. Also larger attacks might require her to charge up her demonic powers. She is just reaching into her immense demonic powers reserves. Because devils need time to mature and develop before they're able to use their demonic powers to the fullest and that comes with time and experience. So is Rias increasing her base demonic powers or just increasing the demonic powers she's able to access at one time and getting used to using it? Because Rias is still a young devil who still needs to develop her demonic powers and as we saw in Volume 23 she's doing pretty well. But let's say this, Rias' amount of demonic power is that of a Satan. We're talking about her base demonic power. But at a young age she's not able to use that demonic power to its full potential yet. So she needs time and experience to basically develop and access her demonic powers. And as she gets older and more experienced then she's able to access more and more of her immense demonic powers until Rias herself becomes Satan-class.

Now you're right about some devils being bad at using demonic powers. Because maybe some of them barely have any demonic power to make use of it or they're just bad at the conceptualization/imagination part of using demonic power. And they're merely better at using magic and the computations and equations part. Because Issei isn't really talented when it comes to using demonic powers. As you saw with Akeno trying to train Issei and Asia with using demonic powers. While Asia just had a natural affinity for it, Issei just sucked at it. The main thing he's good at when it comes to using demonic powers is dishing out OP demonic power blasts(infused with Boost of course), breathing fire(and Boosting it), and his perverted techniques(which he needs Boost to use). Well yeah they're people not talented when it comes to using demonic powers or are just plain bad at using it. Some might have success in some areas when it comes to using demonic power like Issei but suck at the other aspects. You need to have a good amount of demonic power and the ability to use them which is to imagine and conceptualize. And some devils just don't have either one of those. Rias and Akeno are just all-around good and talented when it comes to using demonic powers. They have a great amount of demonic powers and the ability and talent to use them. While some devils might only have some talent using their demonic powers. While some have zero talent at all using their demonic powers.