Sonic blaster

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

History
Captain Jack Harkness obtained a blaster and brought it with him to the year 1941 during his conning days. Jack used it to open a door by removing the lock and, after switching it with a banana, the Doctor used it to blast away part of the wall to escape the gas mask zombies. Rose also used it to create a hole in the floor. (DW: The Doctor Dances)

Jack apparently left it in the TARDIS when he was left behind 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 would later keep the blaster in the TARDIS drawing room. (VG: TARDIS)

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, using it to create 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 have been used as an offensive weapon, but rather as a tool for a means of escape or forced entry. However, Jack brandished the gun towards 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, as 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 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 then was later stated in IDW: Tesseract.