Blessing is better in the sense that it's more reliable, yes, but does this really warrant a +1 
cost with no other advantage? Doesn't seem right, seeing that the only "reliability" it gives is ensuring that 2 attack compared to chaos power. Secondly, Deadly Poison achieves this 3 damage better than Blessing does with increased reliability. I think it should be increased to at least +4|+3 or +4|+4 as suggested, in comparison to Shard of Wisdom. Even then, it would still be a lot weaker than Shard of Wisdom, but that card is pretty overpowered anyways (+4 attack on an immaterial is worth a lot more than on a non-immaterial) so I won't buff Blessing to be on par with Wisdom.
Making it +4/4 would make it better then wisdom in almost every regard, barring use on immortals. And would make it that much better then chaos power, barring a +5/5, which is already rare as is.
The cost of +4 attack on an immaterial target should be higher for +4 attack on a killable target, explainable by the fact that every immortal creature should have a higher cost and less damage than any of their vulnerable counterparts. The argument that it's only "utulizing" a creature's immortality isn't a good argument either, as seen on the example of using Wisdom on an Immortal - it's basically like playing two immortals for much less quanta, while bypassing most shields in exchange for two very situational counters. Shard of Wisdom makes any immortal creature unkillable, thus the point of adding 4 hp isn't comparable to Wisdom. But then, looking at other balances, Shard of Wisdom's effect is similar to Momentum which is also supposedly the cost of one card + 1 quantum in upgraded play. Overall it packs much more benefits than blessing, the only backdraw is that it can only be reliably used on immaterials, which is in-element anyway, so it doesn't really make a big difference.
Perhaps the only real argument is that Blessing is more splashable on other elements, but then again Chaos Power is much much better for that. It can be ran off the mark while not having any real disadvantages. I vote on cards that are situationally better needing to cost more, but if its situation condition is something that you can control while deckbuilding and not simply in response to the enemy's deck, I would highly disagree.
