Sonic blaster

A sonic blaster was type of weapon available in the 51st century. They were produced at the Villengard factory.

History
Captain Jack Harkness brought a sonic blaster with him to the year 1941 during his con man days. He used it to open a door by removing the lock. After switching it with a banana, the Doctor used it to blast away part of the wall to escape the gas mask zombies. Rose, who called it a "squareness gun" because of its blast pattern, used it to create a hole in the floor. (DW: The Doctor Dances)

Jack apparently left it in the TARDIS when he was abandoned by the Doctor. (DW: Parting of the Ways, CON: The Last Battle) The Tenth Doctor denied permission for Emily Winter to take the sonic blaster as it was reserved for "someone else". (IDW: Tesseract)

The Eleventh Doctor kept the blaster in the TARDIS drawing room. (VG: TARDIS, The Gunpowder Plot )

By the time River Song used it, the handle had changed from a dark brown to an ivory colour. (DW: The Doctor Dances, Forest of the Dead) She used it to aid herself and several others in escaping the Vashta Nerada, by making holes in the wall and floor. (DW: Silence in the Library/Forest of the Dead)

Abilities
The blaster used digital technology to create a sonic wave, projected into the form of pulsing squares of blue light, which could cut through thick walls. It also had a reverse function which could replace the removed chunk of material afterwards. This was deemed a "special feature" of the blaster, and was said to use up a lot of the batteries on which it ran. (DW: The Doctor Dances)

In the hands of the Doctor and his friends, the blaster was never seen to be used as an offensive weapon, but rather as a tool for a means of escape or forced entry. However, Jack brandished the gun at those infected by the nanogenes and explained that the blaster could also function as a sonic disruptor and a sonic cannon.

The blaster did not seem to affect humans. When Rose used it to create a hole in a floor, it did not injure her, Jack's or the Doctor's feet in the process. (DW: The Doctor Dances)

Behind the scenes

 * Production staff referred to this weapon as the "squareness gun" before the Tenth Doctor called it by that name, although Rose did so in The Doctor Dances.
 * The idea of River's gun being the one Jack left in the TARDIS was suggested by Steven Moffat and was later stated in IDW: Tesseract.