If it is a plague of Darkness then it is not Darkness itself to blame, but an imbalance. Light may banish it, but where is it being banished? Opposing elements can neutralize each other, if met with equal force, but not truly destroy. Regardless, if you do not know the source of the imbalance then it is liable to simply come back again.

[ She pauses at that; hesitant. ]

I know not what a daemon is, but if it is not touched by Light then I am assuredly not one.