Nightwatcher

Nightwatcher
This unique blade first appeared on the Sword Coast nearly 200 years ago in the possession of a grizzled old adventurer who claimed to have found it in an ancient ruin deep within the Great Desert, Anauroch. The old man gave it as a wedding present to his eldest daughter's fiance, and since then it has passed from father to son for four more generations until a distant grandson used it to payoff his gambling debts.
Nightwatcher changed hands with bewildering frequency over the next 50 or 60 winters, showing up all across the Realms. It was finally purchased by an eccentric adventurer who met disaster in a battle with trolls 30 years ago. It has not been seen since (until now).
Nightwatcher is a rapier with a very sharp, black-adamantite blade with a silver pommel,
worked in ivory and set with a large, black pearl (worth 500 gp). It is a +2 weapon that radiates no light.
The sword's bearer can see at night under an open sky as as if it were daylight. All magical darkness within 30 feet of the blade is dispersed, though darkness of natural origin is unaffected, except as noted above. When planted firmly into the ground, Nightwatcher hums loudly if anyone with intent to harm its wielder approaches within
60 feet. This functions even if the thugs are concealed or invisible, though Astral and Ethereal creatures cannot be sensed by the sword.