How to get Sunder - Elder Scrolls: Morrowind
Requirements: Levitate/Jump buffs to get over ghostfence
Video: How to get Sunder
Sunder is one of the two Artifact weapons required for destroying the Heart of Lorkhan during the final quest of the game, The Citadels of the Sixth House. In order to obtain Sunder you'll need to venture to the dungeon of Vemynal which is northwest of Dagoth Ur. Like Dagoth Ur this dungeon is on the inside of the Ghostfence.
You'll find Dagoth Vemyn inside of the Hall of Torque portion of this dungeon, kill him and loot Sunder from his corpse. He also drops the Amulet of Heartheal which is one of the many different Amulets you can obtain by defeating the Dagoth mini bosses in each dungeon within the Ghostfence.