One Thousand Broken Dreams was a unique magical elven warblade.
The sword was thousands of years old by the 14th century DR. It was made by an elf worshiper of Sehanine Moonbow named Datharian Mistwatcher when his home city was destroyed by the drow. Soon after, Datharian was slain in battle against an army of driders, and the sword passed into other hands.
The sword later came to a female elf known only as the Stargazer, and she slew hundreds of drow with it. When she realized her sister had been killed in the Battle of Nine Arrows, she died of grief, whereupon another elf, a young archer, picked up the sword and left before drow reinforcements came.
One Thousand Broken Dreams came into the possession of many different elves since then, typically once every few centuries, before disappearing again.
There was a rumor that if the longsword was ever drawn by a good drow, it would shatter into a thousand shards of moonstone (each worth around 50 gp). These stones could each be used to cast atonement on a drow and thus redeem them.