Fellow DA main here as well (in Aurora). I agree with everything about Demonic Frenzy; it needs to be adjusted for us to take full advantage of the final damage % buff while not risking certain death. At this point, I just rely on Demonic Frenzy's Max HP % damage reduction alongside Forbidden Contract just to stay alive. Don't get me started on using Demonic Blast.
Regarding scrolls to contain more HP, I also agree as it affects the DA's late game damage scaling but I just want to hope that there may be potential changes coming to benefit DA's, slowly but surely or I'm being too optimistic. One example I can think of is that before, Dojo Gloves only gave All Stat % but Nexon substituted All Stat % for Max HP % for gloves eventually. It was years ago but it was sort of a big change for me. So in conclusion, I am hoping they can implement for changes to better help DA's.