Atlea and Beyond
Olrithax, the Guardian of Hestavar
A dagger made from the horn of a dragon named Olrithax.
The dagger grows stronger with its user. It is a +4 dagger and the user may, as a free action once per day, teleport behind any enemy within sight range and attack them immediately.
This dagger is made from the horn of a dragon named Olrithax, who was the guardian and caretaker of Hestavar (perhaps the most well-known divine bastion of civilisation and knowledge) for thousands of years. When Olrithax was resurrected by Vecna against its will, it begged the party to destroy it and set it free. Once set free, it refused to be raised again by Vecna, instead forming itself into a weapon for Seven.