The angrier one was, the harder it was to control one's power and choices. This was especially true for one whose anger had reached the limit; their judgment would be completely clouded by rage.
People under such a state were predictable, making them easier to deal with.
However, there also existed a special state of mind within that rageful state called Tranquil Fury. It allowed the being to have full control despite angry beyond belief.
Such a special state of mind, which combined the advantages of anger and calmness, would make a person even stronger than their usual peak combat effectiveness.
Vaan didn't expect the Vampire Lord to enter such a supernatural state after being angered by him.
It completely nulled his previous efforts.
After the Eighth Progenitor entered [Tranquil Fury], he did not rush to attack Vaan again. Instead, he dusted his messy black and white suit and cleaned up his appearance.
