The Spine of the Saracen is a device that attaches itself (sometimes forcibly) to the human spine, amplifying the electrical impulses of its host while boosting his or her adrenaline and testosterone levels.
The Spine was once used by a Turkish warrior cult during the First Crusade in the 11th century, and "requires a lifetime commitment" insofar as it will not detach itself from a host until that host is dead. The Turkish warriors who used the spine were supposedly unstoppable in battle. The Spine attaches itself to the T2, T4, T7, and T9 vertebrae in order to access the spinal cord and communicate with the brain of its host.
The spine is powered by the user's own natural bio-electricity, amplifying it in the process; the excess electricity is perpetually discharged by the spine and host body, which causes anybody that the host touches to be electrocuted. Claudia described the enhancing effects of the spine as "ancient PCP" -- it vastly increases the output of testosterone and adrenaline, increasing strength and aggression of the host several-fold, essentially turning a person into a killing machine.
The Spine also generates intense anger in its user, causing them to seek out and vent themselves on the object of their hatred. The Spine will typically drain as much energy as it can from its host until they die, then leave them and seek another. As mentioned above, the Spine carefully regulates the amount of electricity it uses by discharging the excess; if the Spine is overloaded with too much electricity, then it will detach itself from the user's body.
The artifact was discovered at a museum when a series of burned bodies started appearing shortly after an 11th century exhibit passed through; it's believed the spine was sealed in a container, but escaped somehow. The Spine once attached itself to Warehouse 13 agent Jack Secord, so he had himself walled off underground to prevent it from attaching to anyone else. His body was later unearthed when the building exploded, and the Spine became attached to Sgt. Clark, who subsequently went on a rampage, killing off local gang members. After Clark died, the Spine fused with Warehouse agent Pete Lattimer, who eventually managed to detach it with a surge of electricity. After being detached from Pete, the fleeing spine was shattered by Rebecca St. Clair, who transferred the pieces to the Warehouse, before returning to Saint Louis.
In "Endless Terror", Paracelsus traveled back in time and altered history to make himself sole authority over Warehouses 9 through 13. In this alternate Warehouse 13, Paracelsus commanded a small army of super soldiers that each had a Spine attached to their backs, obviously Paracelsus found a way to duplicate the spine and better control its' down side.