User blog comment:Gary299/High School DxD BorN episode 4 review/@comment-3965848-20150425170243/@comment-1359322-20150425172313

Well even if it's made of demonic power i think it'd still be a normal one too. Just part of the elemental Demonic Power. You don't hear the term Demonic Water or Demonic Fire in the story after all.

Plus the Holy Lightning is created by adding Light (Angel/Fallen Angel) with Lightning. It's not 1 element but 2. Akeno even said so in Volume 5.

"“It seems it was useless. She tried to reverse the thunder, but what I shot just now was lightning. Thunder and light. The reverse of the light portion wasn’t enough to reverse it all.”"

- Volume 5, End Game