The laser screwdriver was a device, similar to but larger than the Doctor's sonic screwdriver, used by the Master. It was laser-powered and incorporated various technologies, for example it could age people based on the technology developed by Professor Richard Lazarus. (DW: The Sound of Drums)The device featured "isomorphic controls" so only The Master could operate its functions as revealed when the Doctor attempted to shoot him with it (DW: The Sound of Drums). It is unknown what effect the Laser screwdriver would have on a deadlock seal.
Laser screwdriver. Who'd have sonic?
The laser screwdriver could also be used to kill with a laser blast emitted from its end. (DW: Last of the Time Lords) It is unknown if it would have the same effect on people if it hit them in the leg or arm instead of the chest. It is also unknown if it could be used to age and kill someone while they were under its effect or if they would die after they were released.. The Master attempted to use it to kill the Doctor but was telekinetically disarmed of it by the Doctor using the powers he gained from the psychic energy of everyone on Earth. It is unknown what happened to it after this.