This follows along with that I think, if you remember whenever the Kandra were in a humanoid form their Blessing spikes were always located in the region of their "shoulders"
I think it's the idea that of the 300 or so possible bind points by activated points I dunno let's say 161 and 162, with hemalurtic spikes it changes the mist wraith enough to promote sentience and recover any previous memory. The fact that by the nature of Hemalurgy something must be taken to charge the spike creates the blessing.
To sum it all up, in the technical sense spiking mist wraiths is intending to give them the Blessing, with the sentience as side effect that the Lord Ruler discovered in his "phenomenal cosmic power" state.