User blog comment:Prof. Draco/RP/ Cursed be he.../@comment-1674153-20130608215450/@comment-3270170-20130608235716

(Because he had accelerated the dagger's time to a point where it had long since rusted away. To fix it, he reversed his power. The clock was not destroyed by accelerated time. A reparo charm (hint: GET A HP WAND PROP!) could fix it though.)