The Broad Sword 'Arunruth' (3d5) (+20,+12)
+4 dexterity. Slays demons, orcs. Provides resistance to cold. Cannot be harmed by acid, electricity, fire, cold. Slows your metabolism. Feather Falling. Prevents paralysis.
When aimed, it creates a frost bolt with damage 12d8. Takes 50 turns to recharge.
Min Level 20, Max Level 100, Generation chance 2, 15.0 lbs

(Angband 3.1.2v2)