Hunter's Amulet (Hircine's Hunt) Location - Morrowind
Location: Hircine's Hunt dungeon
Requirements: Completed the entire Bloodmoon Story Quest chain
Both of the Hunter's Amulets as well as the Spear of the Hunter are all rewards for completing the Bloodmoon Expansion Pack's main story quest, Hircine's Hunt. It's the final quest in Bloodmoon and you'll have to complete about a dozen quests before you reach this one... However the rewards to this quest are some of the best in the game.
Depending on which reward you want you'll have to face a different aspect of Hircine with different abilities. If you'd like to learn more about these aspects or this quest I recommend you check out the UESP Hircine's Hunt Quest Walkthrough for more information.