Shell Fragment from the V-1 Doodlebug

Origin
Known as (one of) the Nazi's secret weapon, this bomb was the first self-guided missile to be fired and caused massive destruction in Britain. This shard of metal was all that remained of the first bomb and gained destructive powers.

Effects
When it is applied to any object and the user is concentrating on a person or place, the metal will attach itself to the object and become a bomb in itself. The slightest nudge will send the object flying, and when it lands on or near the desired target, an explosion equal to the original detonation will be released. The shard always remains undamaged, but will not return to the activator, giving any survivors a weapon to use themselves. If no particular target is concentrated on, the artifact will not attach or detonate.