Weapons are miniature Beacons that infuse into each Player's chest. Found in Round One, Task One - the weapons provide a significant advantage to their holders - in fact, it's essentially suicide to attempt to continue through the rest of The Game without a weapon.
Weapons confer functional immortality on their wielders, reviving them repeatedly upon their deaths. This revival ability is limited, and after enough deaths, a wielder will remain dead, barring resurrection magic. The method of limitation is unclear - whether the weapons recharge over time, or whether they have only a limited amount of revivals, or some other limitation - it is currently unclear.
Not only this, but the weapon has also showcased the ability to bounce back damage when a Player is attacked by someone that does not have a weapon. Some sort of temporal anomaly causes the damaged Player to skip the injury on repeat for a second or two before a flicker incurs - the attack now being delivered to the offender instead.
The weapons also confer the ability to use the Catalyst's powers - the only power that can harm a Catalyst or defend against them. Mastering their use takes a great deal of time and practice, however - and uncontrolled use can be lethal, internally igniting the wielder and causing them to burn to death. Players seem to take on aspects of certain Catalysts when progressing through the phases of the weapon's activation. Currently, there is no concrete explanation as to how these visages are determined for the Players.