The hyur girl, Fye (spelling?), used her own life energy to fuel her whm spells. She deliberately refused to learn the proper means of casting healing spells and was a threat to herself. This may be why, in those eras mentioned, that white magick was banned through whm ignorance as to a proper source for channeling their heals.

As for who was using white magick before conjury was created this could well be individuals like Fye and her mother who could , unknowingly, tap into their life force to cast powerful heals.

And if these types of healers were busy accidently killing themselves through Raise, could they have revived or will they in 2.0 revive so and so's given that they are unbound by the conjurer's rules.