User blog comment:Trihexa/Dragon Ability - Outrage/@comment-24502975-20150606203749/@comment-24502975-20150606215402

Serious Shiva and Indra are way more powerful. Normal Shiva/Indra probably aren't, since the Heavenly Dragons are said to be above the Gods.

Rizevim losing an arm to Fafnir (which he restored) has nothing to do with power levels. Issei was able to beat up Rizevim for the same reason Fafnir could - surprise factor. If Rizevim was fighting seriously he would easily kill them both. He's a Super Devil.

...What does demonic power have to do with arms? Anyway,

"Lilith stood in front of Rizevim, and made a line of defensive barriers — Fafnir’s charge hit and he crushed barriers under his teeth, and was slowly, slowly approaching Rizevim! Lilith cancelled her barrier, and directly hit Fafnir’s face! A loud noise echoed through the sky, but the Dragon King seemed unaffected. He swept with a horizontal kick, and sent Lilith flying! What a brutal attack! Although Lilith was unscathed, the fact that she was sent flying is true! Before Lilith could get ready again, Fafnir faced Rizevim and blasted out a massive fireball! Rizevim moved slightly and used his magic to dampen the flames — but the Golden Dragon King was no longer in front of him! He flew up into the air! Fafnir’s massive body was strange with wings; he flew high up into the air, and then aimed his teeth at Rizevim below!"

Lilith did not use her physical strength to stop him, and she also canceled her defense barriers. Lilith being unscathed implies Fafnir's attack didn't do anything to her, and she didn't get back in time to protect Rizevim again (I'm not entirely sure, but she either didn't bother to use Godspeed or doesn't actually have the ability). So "she couldn't stop Fafnir" is wrong.