A laser was, in a description posited by Leela and approved by the Fourth Doctor, a very powerful light. (TV: Horror of Fang Rock) Many lasers were harmless and used in some games, but others were used as deadly weapons. During their campaign to recruit warriors, the Uvodni utilised harmless laser weapons in their interactive laser-tag game Combat 3000. However, on board their ship, the Kudlak warriors carried deadly blaster rifles that fired a yellow laser burst. (TV: Warriors of Kudlak)
In the video game Attack of the Graske, which this wiki does not consider to be a valid DWU source as it has multiple endings which we cannot qualify through any mechanism which one is the "correct" or "canonical" one, Graske on the planet Griffoth were shown to be armed with tiny laser pistols which fired purple blasts to combat intruders.