Defabricator

The defabricator gun was a custom-built weapon built by Captain Jack Harkness in the year 200,100, which was bult using parts from the Trin-e and Zu-Zana robots. The weapon fires a bluish beam of energy that was capable of piercing Dalekanium armour and destroying a Dalek. (DW: Bad Wolf/The Parting of the Ways) Its original purpose, however, was to automatically remove clothing. Jack killed a Dalek with this but said that it depleted its power source.

Jack had somehow managed to have brought this weapon along with him when he transported himself back to the 19th century and used the weapon again to destroy several Daleks (the beam was also capable of destroying the Red Dalek) when the Earth was stolen by the Daleks. Apparently this time he had replaced the power source with a better one as he was able to use it at least twice: killing a normal Dalek and the Supreme Dalek. (DW: The Stolen Earth/Journey's End)