Possessing sufficient mental strength wasn't just one of the key requirements to a witch's successful breakthrough; it was also the most important.
However, simply possessing sufficient mental strength was far from enough; careful usage of it was also crucial.
Just like the best result in a marathon race couldn't be achieved by sprinting from the start, the same applied to witches advancing their ranks.
Use too much energy, and one won't be able to finish the race. On the other hand, use too little, and one would take too long.
Hester possessed sufficient mental strength to advance her rank, but she had used too much mental strength at the start, and no longer had enough to complete her third mana ring.
Although Vaan wasn't present at the start of Hester's breakthrough attempt, he could guess that much due to the person's anxious expression.
