A device for securing a weapon with a safety, the device having a safety body adapted to contact a sear of the safety, and a movable actuating element between a first position and a second position. The actuating element and the safety body are adapted to make the device configurable between at least: a firing state wherein the actuating element is in the first position, causing the sear to slide through the safety body; and a safe state wherein the actuating element is in the second position, causing the sear not to slide through the safety body. Also, a trigger mechanism housing and a weapon which include the device and a method for securing a weapon by a safety of the weapon and a device for securing a weapon.