Blackheart is an ancestral weapon of House Dragomárus. It is one of the oldest dragonsteel long swords in the known world. It has been missing, and no one is sure if the sword has been taken up by someone else, or if it has been lost to the elements forever. It was previously wielded by Aenarion Dragomárus and his descendants until it was lost; the last known wielder of Blackheart was Draegon I Dragomárus.
Speculation
It is currently unknown where the blade currently rests, however historians and nobles alike are interested in the whereabouts of the sword. The blade has been missing ever since the death of Draegon I Dragomárus approximately 300 years ago. Some believe he lost it during battle, but this is impossible, since he knighted his son Daenar shortly after his coronation.
Due to the vast halls and networks of passageways built in Dragonspire, it can be speculated that the sword may have been hidden deep within, but no one has known how to access them in centuries, and it may simply be that the sword has disappeared from prying eyes, its whereabouts only known to House Dragomárus for practical reasons.