Trinkets is an item class. They are a miscellaneous type of equipment. There is only one item basetype in this item class: Thief's TrinketThief's TrinketCorruptedYou must find the sculpture The Catch in a Smuggler's Den or Underbelly Blueprint to be able to equip this.
Thief's TrinketsThief's TrinketCorruptedYou must find the sculpture The Catch in a Smuggler's Den or Underbelly Blueprint to be able to equip this can be found during Underbelly or Smuggler's Den Grand Heist. They provide item drop bonuses within Heists. Trinkets can have up to four affixes and drop corrupted. Only the person who triggers the item drop by killing the monster or opening a chest will have their Trinket effects applied to the drop. Other party members' trinkets will be ignored.
The trinket item slot is unlocked by running a Smuggler's Den or Underbelly Grand Heist and clicking the "The Catch" Sculpture located within the final reward room.