The elemental weapons not being absorbed part makes sense.

As for what you said about Meteor being Holy Elemental, I'm not so sure. I remember casting Meteor on the four fiends combined when they were in Scarmiglione form, so if Meteor is holy elemental, he shouldn't have absorbed it because undead are weak against holy.

Then again, in the bestiary entries the only six "elements" that enemies can absorb or be weak to is ice, lightning, fire, holy, darkness, and air attacks (like arrows). Meteor would probably fit the best under holy between those six.