Um. You might want to read what I write before saying you agree with it. While I did not say the opposite of that, I did not say that either.
So do you agree?
Rather than answer I will analyze.
The shard is underpowerd if you combine it with creatures other than immortal creatures. If you want to make good use of it, you have to combine it with an immortal creatue. these creatures are EXPENSIVE. you can also try to combine it with any creature and then quint it, but this makes you lose even more card advantage. If you add all of these negatives together you will realise that this card is balanced as it is.
Non immortal creaturesBlessing vs Shard of Wisdom
Cost: 3
+ 1 card
Effect: +3|+3 vs +4|+0
I am ambivalent between these choices. This is evidence to me that Shard of Wisdom used on mortal/material creatures is UP IFF Blessing is UP. The same form holds true for OP and balanced. So how is blessing? (UP, Balanced, or OP?)
Immortal creaturesWhy would the cost of immaterial creatures matter? If they are balanced, then the cost is already accounted for. If they are imbalanced, they should be rebalanced and then the cost would already be accounted for.
Why would the card disadvantage of Quint matter? If Quint is balanced, then the card disadvantage is already accounted for. If Quint is imbalanced, it should be rebalanced and then the card disadvantage is already accounted for.