Leather Collar of Giant Slaying

is one of nine powerful Ephemeral Relics that can sometimes be found in different areas in New Britannia. These items are Pet Equipment items that can be equipped by Tamed Pet or Summoned Pet creatures.
 * The Companion Magic Resistance item effect value will be different for all players. This value is possibly related to the players Adventure Level.
 * Item properties updated as of Release 112.

''This leather collar is embossed with glowing pictograms depicting giant creatures such as trolls, the phoenix, and the ominous frost giant in various death poses. This extremely rare and powerful Ephemeral Relic cannot be repaired and features a very low durability, so this item can only be utilized for a short period of time before it is fully depleted. Once depleted, salvage this item for potentially valuable crafting materials.''

Found
This item is rumored to be found somewhere within Despair...