It has long been recognized that the initial impact of a Phaser strike on a shield system is the most damaging part of the firing sequence. Many cultures have sought to increase weapon effectiveness against shields by developing pulse cannon - that is, weapons which fire large numbers of tightly packaged bursts rather than a continuous stream. Early Federation vessels such as the Constitution class where equipped with such pulse cannon, but the weapon is not without its drawbacks. The hardware involved tends to be very difficult to manage precisely, resulting in much poorer control over the beam characteristics. The Federations Starship design ethic has always stressed that full control must be maintained over all weapons at all times, in order to allow non lethal force to be used in Starship combat situations. In addition, many scientific experiments use weapon systems to apply energy in controlled amounts to external phenomena in order to study reactions. Given this, the Federation gradually moved away from pulse cannon. The refit given to the Constitutions in the 2270's removed the pulse firing feature from that class, equipping them with a 'rapid burst mode' which was something of a compromise between pulse and continuous Phaser beams. Further designs continued to de-emphasize the pulse firing feature, although all basic Phaser hardware is capable of firing relatively short bursts and this has remained a feature of Federation combat tactics.

With the development of the U.S.S. Defiant, the pulse Phaser cannon was finally reintroduced to Starfleet. Defiant is a warship, pure and simple. Her designers had no real interest in conducting experiments, and the attitude towards the level of lethality of her armament could perhaps best be summed up by the phrase 'take no prisoners!" Defiant's main armament comprises four heavy pulse cannon which fire very tightly confined bursts of Phaser energy for maximum impact on shielding systems. High overall energy delivered over a very short period combines with a high firing rate to produce a performance against modern shield systems which can best be described as devastating.

On her first active mission the Defiant faced a group of Dominion Attack Ships. These vessels had successfully withstood several minutes of fire fighting with a Galaxy class Starship, but Defiant's Phaser cannon cut through their shields within moments. Subsequent combat experience has shown the value of this weapons system, which is currently being developed for use in other vessels.