In fact, she wouldn't truly die, as she was a Vampire, and no matter what happened her body would start to regenerate and recover.
But she would definitely suffer a heavy injury and would lose a considerable part of her strength to recover.
In this situation losing strength was the same as dying, that was why she thought she had totally lost at that moment.
Just as that gloominess overcame her, and she thought that most likely she would end up dead in this battle, her sword disappeared from her hand, as a small knife appeared.
It was a truly well-crafted knife, with exquisite details, and truly beautiful, but the most important characteristic wasn't its craftsmanship and details, but the sense and power it gave.
The Ruthless Princess wasn't calm enough to sense that, as she was more startled from what had just happened, and just used it instinctively.