Kerrasone is perhaps the most unique sword ever created, and is the only known shape shifting sword in existence.
It has several Gems in the hilt and the blade is made from an unidentified
metal. At the bottom of the hilt is a crystalline dome filled with a pale green
liquid. Inside the dome is a shard of Onyx shaped like an arrow. The onyx lazily
spins in circles within the liquid like a compass that can't find North, until
it is in range of one of the shards of Karith's soul. Then, it points directly
to the bearer of the shard, often alerting its wielder either out loud or telepathically.
It will not willingly help a non-good creature find the soul shards.