I did some testing last night since I noticed a bit of odd behavior when I was using puncturing sweep.
Below is a portion of my CLS log as I used puncturing sweep over and over again on a VR10 Mammoth in the Rift:
Notice that the damage caused by burning light is used to calculate the healing of two of the puncturing strikes.
Below is a portion of my CLS log as I used puncturing sweep in combination with blazing shield and channeled focus:
Notice that the blazing shield crit damage is used to calculate the healing amount of one of the strikes.
I'm not sure if this is intended. I tried my hardest to get the heal amount based on the damage of power of the light but I couldn't seem to get it, maybe it is just a timing thing. I have a feeling this bug might be limited to damage caused by a spear ability.
While it is apparent that this could be a bug (or problem with how CLS works) I would also like to mention that it works both in the player's favor and not in their favor. Specifically, the heal may be based on a damage tick from blazing spear and will result in much less healing done.