I'm a fellow physics-maker myself, so I can tell you all the ways you can make your next version less bad.
First off: Grenades? From a pistol? Tell me, what were you trying to accomplish here? There's a reason you don't start on ne cede malis with a grenade launcher- it would be kind of broken against anything in standard.
Next- the fusion pistol: Not only is there an unnecessary number of fusion overload bolts flying around (juggernaut, vacbobs), but you don't get to shoot them yourself! Incredibly frustrating.
Shotgun: The concept of hunter bolts as bullets is nice, but they don't travel fast enough to be effective. In other words, by the time the shotgun bullets reach the target, I could have killed it with something else.
Assault Rifle: The AR has a frustratingly low rate of fire, but the power tries to balance it out. Not too bad.
However, the AR is ruined by the second trigger. If you're going to make a charge weapon, at least tell the player they're charging it. P&V is cool, but I've heard it can crash the engine sometimes. It also doesn't make up for doing hardly any damage.
SMG:Again, with the hunter bolts being too slow. If i'm in a multiplayer match, they're incredibly easy to dodge. I'd recommend upping the speed to 768 at the very least.
Flamethrower: It's a nice idea, but i'd recommend again making the shots go faster. It's no fun to shoot at a moving target only to watch him be twenty feet away when the bolts hit him.
Rockets: Not bad. I like the dual shot, just make sure it isn't too powerful or too weak.
Alien weapon: This weapon is really dangerous. The concept of "one giant shot that kills everything" is not in itself a bad idea, but the blast radius is so huge that it's hard not to kill yourself too. If you set it to 32767, the highest it goes, it's determined by polygon borders instead of how far you are from it and that's just obnoxious. If P&V belongs in this model, it would be here. I'd still give it more than one shot though- three maybe?
Last, the aliens are not fun to play against. Enforcer major bolts will toss you in a corner faster than you can move and that's BAD. And the juggernaut with major fusion is ridiculous. Please don't have him. So anyway, if you need help you can PM me on the pfhorums and I'll be happy to help.