The Dagger of Rilia (2d4) (+14,+13)
Slays orcs, trolls. Branded with venom. Provides resistance to poison, disenchantment. Cannot be harmed by acid, electricity, fire, cold.
When aimed, it fires a stinking cloud with damage 12. Takes 5 to 8 turns to recharge.
Min Level 5, Max Level 75, Generation chance 5, 1.2 lbs

(Angband 3.1.2v2)