Great Key

"Or it's a key all the time and when you stick it in people, it unlocks their death." - When Caboose and Church discuss the function and true form of Tucker's Sword.

The Great Weapon is an energy sword Tucker finds in a hole under the windmill in Zanzibar while the group tries to assassinate O'Malley. It is later revealed by Gary a thousand years ago to be a relic of a long lost civilization(Forerunner). The alien needs it to fulfill a prophecy to become leader of his race. At the end of a long quest, the sword is revealed to be a key to unlock the alien's ship, which Tucker comments on "the sword is a Key? Can this quest get any lamer?" After Wyoming kills the alien and busts the ship, Tucker and crew return to Blood Gulch where the sword becomes his main weapon of choice, but still pines for the sniper rifle. At the end of the season, Tex steals the sword and kidnaps Tucker's alien baby because only Tucker and Junior can use it. When Andy blows up the ship they were on, it was believed to be destroyed.

At some point, Tucker was able to reclaim his sword and in the mean time acquired a great deal of skill with it, as he was able to use it to kill several of the 'excavation team' members with ease, albeit off-screen.

However, it can be assumed due to both the aliens and Gary lied, as the great weapon may not be as great as the prophecy fortells.