User blog comment:EmpyreanSmoke/Weaknesses/@comment-69.64.58.255-20151001035430

The mass of normal angels are not as powerful as archangels and 99 percent of the demons are not as powerful as Lilith, Alastair and Azazel, so just because a Leviathan may be able to kill or eat a low powered one it doesnt mean they can do the same to the more powerful ones. The transitive property doesn't apply here, because archangels and the three demons in particular are on a whole nother power level from the others and may not be killed the same way. The older or more powerful ones also have more knowledge of magic, and as we saw the husband witch do in the Winchesters hotel room, magic can actually easily disable a Leviathan. If you want to still use the transitive property, Meg was able to disable a large number of Leviathans in the same episode Imperiexseed is talking about, and she was a weak black eyed demon. If she can do that the more powerful demons can do it even better. If we didn't see something in an episode, and if one of the characters doesnt seriously state that it is possible, it shouldn't be in a page here as it might not be true. Assuming is not always right.