3.1 MSQ Reaction [SPOILERS]

[CyrilLucifer]

He also seems (flatly) annoyed that the duo was actually killed and that he has to clean up their mess.

Unrelated, but I found Elidibus hilarious in the epilogue. I mean, it's common for antagonistic characters in Japanese games to be apathetic about their colleagues dying, but Elidibus actually bothered giving a rather lame "boo hoo," before complaining about how much blood there was on the floor from their bodies.

If nothing else, he is pragmatic enough to see that the loss of an ally, no matter how rogue, is detrimental to his cause.

. . .If Elidibus wanted them both killed, he would have supplied us with two; though we don't yet know the rarity of the material, I'm quite confident he could easily obtain it. Why didn't he?

More seriously:

I actually believe Elidibus only wanted Lahabrea out of the picture. Just in the short time we saw Lahabrea in-game he has acted inappropriately, in Elidibus' eyes, at least twice, disregarding anything he might have done in the past because we don't know anything about it. Elidibus gave him chances, hoping he would calm, but Lahabrea didn't; he proved he wasn't willing to learn from his mistakes.

As for why only one auracite - because, as I mentioned above, Elidibus is nothing if not pragmatic. Why lose two when you can lose one? Igeyorhm could possibly have been reigned in. While she was basically given no personality, she didn't seem as rash as Nabriales or Lahabrea. Quite the opposite, actually, she was more level-headed judging by her pre and mid-battle dialogue.

That, paired with you having unfinished business with Lahabrea, makes it an understandable gamble that, with only one auracite you'd choose the Ascian you know rather than the Ascian you don't. The only reason we went for Igeyorhm first was because she exposed her Dark Crystal first in attempt to escape - which, by the way, I think was a rather foolish decision on our character's part, but hey, it's not like we can do anything about it.