Definitely not a fan of Bless requiring a source skill, especially not when it (to me) mainly was used to negate the rampant cursed surface(s) the enemies spit out every other encounter. Not to mention that you also often have to bless random NPCs/objects in order to complete many minor quests.
I realise that there's going to be multiple ways to obtain source in the final release and that it'll be possible to have multiple source points at the same time, but I must admit I'm still not too happy about that change.
I hoped that Bless requiring source points to cast was a GM mode exclusive thing, but after re-watching the Gamescom video it does indeed seem like it's going to be require one source point in the real game as well. At
5:10 in the video Swen demonstrates the bless ability by having Sebille cast it on a fire surface. Sebille's source point is immediately consumed afterwards.