Ascians

[Cilia]

Are the Twelfth X's all Lahabrea's, or are all the Swords and Staves? Or, indeed, only one of the two between Sword and Staff, with the other being a different Ascian lending his underling for a mission?

I haven't done the post-50 SMN stuff either, but...

I would theorize that the "Twelfth X" Ascians are all Lahabrea's underlings. This ties into the Zodiac theme the Ascians derive from the Ivalice mythos. Lahabrea, in terms of the Zodiac, represents Pisces, the twelfth Zodiac Sign, so all of his underlings would be "Twelfth X." By that same token, all of Nabriales' Black Masks would be "Eighth X" and Igeyorhm "Ninth X," but without anything to verify this it's just a theory...

EDIT
Beat to the punch...

On the other hand, the lesser Ascians seem to be named after the Minor Arcana. Not sure if anyone pointed this out yet.

So why isn't Lahabrea able to flee when Thordan attacks him?

Probably because we beat him to within an inch of his life beforehand? Ascians can teleport, but when Igeyorhm tries to do so she takes time to do it - suggesting that, when weakened, Ascians can't instantly teleport. While they do possess pseudo-immortality, the Ascians still have to act in real time; if they could instantly teleport at any time they would be completely invincible without a mortal vessel, and none of them could ever possibly be killed. Nabriales and Igeyorhm would just warp away when we throw the White Auracite at them, Lahabrea would just warp away when King Thordan is about to kill him, and we'd never be rid of the headache.

It's either that or for story purposes.