The Tractor Beam is a special weapon of the game Star Trek: Armada. It is not a weapon in the conventional sense, although it can be used in a similar fashion. A ship targeted with a tractor beam will be toed after the ship using the tractor beam. This only works on ships and only if their propulsion systems are (currently) down. It does work on friendly and abandoned opposing ships. So a ship with damaged propulsion may be toed near a defense station in order to save it. Opposing ships may be captured and towed home. The Ferengi faction on multiplayer also uses this special weapon to drag away unoccupied or disabled ships. It looks like this:

The Tractor Beam is an integrated part of any constructor, so it does not cost anything in addition but is always available.