system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek TNG] Why are more melee weapons not employed against the Borg?

If not melee only, then more conventional firearms or something that uses a slower-moving projectile (since shooting guns on a starship could understandably be disastrous). It reminds me of Stargate when the guy had a personal shield like the Borg so O'Neill just throws a knife through it since it wasn't calibrated to stop slow-moving objects, just projectiles. Bullets are going to move slower than beams of light (plasma? I'm not sure what phasers shoot) Worf had luck with his mallninja knife in First Contact, Picard did ok with a Thompson. I wonder if it's a case of keep it simple, stupid. Granted the Borg are portrayed to be very strong in comparison to humans, but it seems like they also move kind of slow and giving your guys a chance with blades is better than having them stand there wondering why their phaser isn't working until they get assimilated.
gpt
They would adapt, and then all melee/projectile weapons would be useless. Star Trek shields are capable of stopping physical objects. 

At least phasers can have their frequency changed, giving the weapon another chance to be effective, melee weapons have no such capability. 

Add to that, getting that close to a Borg drone is a great way to get yourself assimilated, after all you're in arms reach with a melee weapon. 

(I'd also avoid comparing Star Trek shields with Stargate's. Different tech, different results, strengths,  weaknesses.)