"Probably because that’s the only thing Helen used it for. I don’t think it’s ever seen battle.” Piper looked at the blade again. For a moment, her own image stared up at her, but then the reflection changed. She saw flames, and a grotesque face like something carved from bedrock. She heard the same laughter as in her dream. She saw her dad in chains, tied to a post in front of a roaring bonfire.

She dropped the blade.

The Lost Hero, Chapter IV