Contemplating what the origin beings did, Walker still felt he was missing too much. But the fact that he could pull at life mana without an attachment to a living thing made Walker realize he had never been able to sense it until now. He had missed that.
This rush here and there to do this or that had distracted him from that step. Walker had thought and death manas were mostly what existed within things. Life mana would not be sent out or it would harm the person that did that. They could spur their life mana to help heal to and grow a little more. But that was encouraging the life mana to act and not transferring to someone else.
The same with death mana. Undead had some within and death mana could certainly be sent out/ but it had to have an origin or a cause. It came from the undead or the dead in the area and seeped in because of it. It didn't just float about.