Federation phasers aren’t weak. The federation just prefers to stun people rather than vaporize them. Remember when Data used his phaser to shutdown that power grid? Or the time they vaporized rock with their phasers?

I've never seen a klingon disruptor pistol do that. Have you? or Cardie, or any one else's (though there was that time Quark was trying to sell some shoulder fire artillery...)

we don't know what kind of range or power they really have. Just like how their starships aren't warships, but they out class most other faction's warships.the other factions don't hide what they are though. (and the kind of firepower that can take out damns from miles away is simply unneeded in any battlefield at that level of accessibility.)