A Swiss Army knife was a multipurpose tool.
Ace found a a Swiss Army knife with the letters IC in a sofa in the Doctor's TARDIS. (PROSE: Cat's Cradle: Time's Crucible)
The Seventh Doctor carried a Swiss Army knife with him while in Hong Kong. (PROSE: Bullet Time)
The Eighth Doctor used a Swiss Army knife to break out of a room on the Quetzel. (PROSE: War of the Daleks)
Melanie Bush carried a Swiss Army knife with her in her purse. She used it to break into Sheffield Hallam University. (PROSE: Instruments of Darkness)
The Fifth Doctor compared his Molenski Univarius to a Swiss Army knife. (AUDIO: The Axis of Insanity)