The Type 8 Phaser was a ship-mounted phaser emitter.
In 2293, the phasers of the Excelsior-class USS Enterprise-B were listed as type 8 phaser emitters in the bridge master systems display. (Star Trek Generations production art)
In 2370, the Cardassian warship Vetar came under attack by a fleet of small Maquis attack fighters armed with photon torpedoes and type 8 phasers, which inflicted heavy damage to the Vetar. Gul Evek accused the Federation of supplying these supposed civilians with the weaponry, but Captain Jean-Luc Picard assured Evek that however they got them, it was through unofficial channels. (TNG: "Preemptive Strike")