Well, I was thinking that since it does 1d8 healing, and deals half that in nonlethal, in effect it does half of 1d8 healing before unconsciousness. Plus, the higher level versions are all straight d8s, no bonus from level.
Absolve Light Wounds (Clr 1, Drd 1, Hlr 1, Pal 1, Rgr 2): 2d8 lethal...