There are two sickles to find in this DLC. The Bone Sickle can be found by defeating the legendary animal, The Black Stout, in the north of Connacht. The Ceremonial Sickle can be found in a Wealth Chest in the Druid camp of Lackenscaul in the south of Connacht. Equip both, one on each hand, to dual wield them and earn your achievement / trophy.