The Truncheon is a small device shaped like a warhammer able to erase and restore the memories of its target.
The Truncheon was the weapon of choice of the Kree Vin-Tak. He brought it to Earth with him when a signal from an activated Diviner made him decide to investigate who transformed; he believed that Inhumans were abominations that needed to be destroyed.
Upon his arrival, Vin-tak had a confrontation with the Asgardian warrior Sif who, because of the enmity between the Kree and the Asgardians, wanted to know why he was on Earth; during the battle on a beach in Portugal, he used the Truncheon to deflect blows from her sword. By the battle's end, he used the Truncheon to give her amnesia.
Since the nitrogen tank he used to keep his blue skin pink was damaged in his fight with Sif, Vin-Tak went to a hospital to get more. He used the Truncheon to cause the reception nurse to forget his arrival.
While Vin-Tak was being interviewed by Phil Coulson, Morse was commissioned to study the weapon. She posited that unless Vin-Tak was in contact with it, the Truncheon was an ordinary war-hammer. When Lance Hunter entered, desiring to give Morse a break from researching, she attempted to use the hammer on him to no effect. Morse told Hunter all she had learned about the weapon, including that it had the power to restore memories as well.
As a sign of good faith toward Sif, Vin-Tak used it to restore her memories.
When he discovered that Skye was an Inhuman, Vin-Tak desired to kill her. Morse and Alphonso Mackenzie stopped his pursuit; after Vin-Tak dispatched Mackenzie, Morse challenged the Kree. He used the Truncheon to fight her blow for blow until Leo Fitz hit him with a blast from the Destroyer Armor Prototype Gun. Morse then used that opportunity to grab the Truncheon, and, keeping it in contact with his hand, removed Vin-Tak's recent memories.