Shakuni looked at Duryodhana trying to figure out how he could not see how mature his nephew had become in these short years of his life.
This is a knowledge that even a well-versed and knowledgeable person would not see through or they would not be willing to acknowledge the fact that the one they consider supreme and their lord can make mistakes.
It's easy to just put blame on one person and then to accept their own, The one they think is without any blemish and worship it can be wrong, And the one who is against your deity is evil is a lot more easy to accept than to call the victim.
But Duryodhana at this tender age saw the difference as adults blindfolded themselves to see it. It just hurt his heart because of this understanding of Duryodhana.
