Staser

Staser weapons were the standard armament of the Chancellory Guard on Gallifrey. The Guards were normally equipped with staser pistols, although staser rifles were also occasionally used.

Like most advanced energy weapons, stasers had both lethal and non-lethal settings. They were relatively non-damaging to inorganic matter but caused massive tissue disruption to living creatures. (DW: The Deadly Assassin)

As a result a single staser shot could apparently kill a Time Lord outright by causing so much damage regeneration could not take place. Against other targets the weapons proved less effectively than one might expect of Gallifreyan technology.