Weapons are tools or devices created to inflict physical damage. People use weapons for self-defense, hunting and law enforcement, as well as for crime and warfare. Some weapon definitions include tools that were not originally made with the intention of harming someone, but can be or are used for it. The relationship between blockchain and weapons can be divided in two parts: the purchasing and selling of weapons with Bitcoins or other cryptocurrency; and the usage of blockchain for weapon control, distribution and tracking. The implementation of blockchain into weapons development can be effectively used for supply chain management, the prevention of making unregistered items and the tracking of a manufactured weapon in order to keep it under the laws of the respective government. However, current blockchain interactions with weapons mostly are illegal deals on the black market made with Bitcoin.