Advantage of an Incomplete Pearl
The reason the Viper's injuries are superficial was that they were merely the physical ones and Hal's blood was more than enough to heal them.
This of course did not mean Hal's blood was an all-cure for physical injuries. In fact, Demonic beasts are the only ones able to handle the strain the blood's energy was bound to cause.
That said, more things were worrying about the Viper's current condition which was that it could not form a pearl in the foreseeable future and was now stuck in the sensing beast realm.
But that was something Hal decided he would take care of later.
It would, after all, be such a shame if a powerful beast was rendered useless by its own rash decision.
So I guess you could say Hal saw himself in Sassy's actions.
Or at least himself, when he first arrived here.
With her physical injuries healed, Sassy began to frolic by twisting about Hal's arm.