Benjen said he was stabbed by dragonglass and the WW were turning him, then the Children of the Forest saved him somehow. So he was like, half-turned into a WW. Which is interesting bc we've only seen a baby turn into a full WW. And it was with a touch from the Night King, not with dragonglass. What was special about Benjen that he deserved full WW status? Can they turn anyone into a WW but choose not to? Wouldn't more WW be better than more wights, or do the new WW retain their free will, meaning they choose wisely and mostly use Crastor's baby boys? If so we're again back to "why Benjen?" then. It doesn't really make sense. Is it because he was a Stark?
I doubt it has anything to do with the Lord of Light though, the Children of the Forest is an entirely separate religion/power.