I'm sure this will be hated, but I think that the Covenant sniper rifle in Halo actually solved this very well. It is a powerful weapon, but is relatively slow, and if fired more than twice in succession, it has a damage penalty and a wait time (it "overheats").
Right now, aside from the MG which I will address in a moment, it is the most unbalanced weapon in the game. A person with good hand eye coordination can repeatedly pick off person after person from a distance without putting himself in danger (I'm looking at you Abaddon

The machine gun suffers from some of the same problems. On open maps, such as Succer Socks or Greatwall, the machine gun is often used as a rapid fire sniper rifle. It's secondary fire is much faster than the nex, almost as accurate, a clip of ammo has hundreds of rounds, and it is impossible to dodge (being a hitscan gun). Not to mention that the machine gun inexplicably stops people in mid air, a severe hindrance to movement. The machine gun is fine in close quarters, albeit a bit too powerful imo, but anywhere else it is absurd.
Not only is this discouraging, it is irritating and puts off new players- yes, one of my friends tried out Nexuiz, and gave it up because he was repeatedly pwned by a particularly skilled rail-bitch.
Not to mention that veterans with a knowledge of the console and configs can set up keybinds and scripts which effectively eliminate the only things that might put a Nex user at a disadvantage, the reload time, and the time it takes to zoom.
I do understand that this is not Halo or F.E.A.R, and people dont expect actual team tactics to be used- it usually comes down to who has the faster reflexes/who is on more amphetamines. And a lot of people like it this way.
However, I think the game could be drastically improved with the following changes, which would make the game more accessible to newcomers (especially ones coming from other games), allow people to expand their skillset, and offer more intelligent gameplay:
For the Nex-
• Make it more powerful, but have a 2.5- 3 second delay in between the shots, and eliminate the "feature" where the delay can be reset by switching weapons. That is just stupid.
• Alternatively, allow for quick successive shots, but make more than 2 quick shots in a row incur a damage penalty (maybe 30 hp), and a longer wait time.
For the MG
• The primary fire is Ok, not too accurate. It could be improved however if it "overheated" after say 150 full auto rounds, and a 3 second penalty would be implemented before it would be usable again.
• The secondary fire is absurd. IMO, it should be marginally more accurate than the primary fire, and no more powerful per round, but be a "burst" attack, where say 15 rounds would be shot off in a very short time per shot, but there would be a longer wait time in between.
You might say- "but Torus, the shotgun already has a burst secondary fire"
• Well, that could be easily replaced with a shotgun fire mode similar to the primary fire, but take longer to reload (like the current secondary does), and simply be more powerful. Who ever heard of a burst shotgun anyway?
• Remove the "push" effect of the MG. It is just unnecessary, and really doesnt make sense.
Basically all the other weapons are perfect and awesome in my opinion. The mortar takes serious skill and even tactics with the secondary fire, the hagar is just badass and also is has the "fire round corners" thing, the electro is really unique and possibly my fav weapon, and the RL is just fine IMO.
Thanks for reading this if you did, I wanted to get these gripes off my back. Please discuss- and if you feel this should really be in the other thread about the Nex, please merge it- I thought there were some other related things that needed to be brought up, but I didn't want to hijack the other one.