Another observation, just to keep them together. About the undead:
The souls of the undead (Forsaken, PC death knights, ghouls, etc.) are imperfectly attached to their bodies; the dark magic that sustains them is a buffer that prevents their souls from properly joining with their bodies. This is why undead feel only faint sensations of pain or discomfort from most physical stimuli
from an old blue post but the info is still valid.
https://web.archive.org/web/20120310010947/http://eu.battle.net/wow/en/forum/topic/3313064613?page=3#49
At the moment this info is still valid and does not contradict the recent interview.
What is also known for some time from Ask CDev is
Record of undead emoting positive emotions are rare, though there are reports, however, that some Forsaken have slowly experienced a sharpening of their dulled senses of touch, smell, etc., as well as an increase in the flashes of positive emotions that have otherwise become so rare since their fall into undeath, when influenced by the Holy Light. The drawback however, is that they also become disgusted with themselves and are likely to increase attempts at their own self-destruction; for regaining these senses would force the undead to smell their own rotting flesh, taste the decay in their mouths and throats, and even feel the maggots burrowing within their bodies.
So, here is the deal. Calia is an odd creature. She is so “Light” that even lightforged look like a cheap copy in comparison. And given how the Light affects the undead, it might have a peculiar consequence: regardless of her wanting that, just the presence of Calia might alter the mental state of undead around her.
That is a nice bonus for those who would want to restore as much of their former self as possible, but for the rest, who do not want to become who they were, this can be a rather unpleasant side effect. Especially, given the “they also become disgusted with themselves and are likely to increase attempts at their own self-destruction” part.
Also, that would explain why Calia could ease the state of night elves. She does not need to say them much. Maybe even repeating multiplication table would be enough, because it’s not what changes them - it can be just a side effect of the essence of naaru that sustains her now.
And it adds another thing to look for in the future: will Lilian notice the difference in the way she thinks and feels when there is no Calia around, and when she is close?
edit: it does affect the living too, but so far there are only pronounced effects on those who “accepted” / chose to follow the Light, like Anduin. So, won’t have much role on for the horde members, but can have some on the alliance ones.
gl hf