Eleidon's Ward in Ibar-Dad - Elder Scrolls: Morrowind
Requirements: Able to open a lock level of 70
Video: Where to find Eleidon's Ward
The best shield in the game, Eleidon's Ward, is found in the Ibar-Dad dungeon. You'll be running by this dungeon multiple times while doing the main story since Ibar-Dad is located between Khuul and the Urshilaku Camp, a location you'll be visiting for many story quests. Use my map screenshot below if you need additional guidance with finding this location.
You can find Eleidon's Ward along with a couple pieces of Daedric Armor in the back of the cave. The door that leads to the treasure room has a lock level of 70 so make sure you come prepared. Eleidon's Ward is the shield hanging high up on the wall, you'll need to jump to reach it. Assuming you have an Acrobatics skill of 30 - 40 you should have no problem reaching the shield.