"Curse of Responsibility"
Responsibility was a good thing for responsible people, making them a good person who would be liked by a lot of people.
Their life quality would also be better by leaps and bounds.
But just like the two sides of coins...responsibility also had its own curse.
Responsibility was as heavy as a mountain. It was a burden at one point, and it was also as restrictive as a cage.
People with a lot of responsibilities will feel an unknown burden on their shoulders, as if a mountain was pressing down on their whole body.
This was what happened to the Valkyries with the curse of responsibility.
Most of the high-level Valkyries had huge responsibilities, so even if they could purify the curse, their own soul and body resonated with the curse.
It was too late to do anything.
BOOM!