Umm

Use kennys duel weild script. It doesnt sync though. After 3 or so duel weilds it stops syncing altogether.

Yes, exactly that. Otherwise, its the fake dual wielding that has been around for so long, and somewhat works. Its just a fancy thing anyway, and it takes up your screen....

This would be a definition of "not syncing"

Maybe you could make a weapon that hits twice as hard as normal and goes through the ammo twice as fast (maybe double clip size and make one shot take two bullets... dunno how to do it for energy weapons tho). If possible, make it so you can only hold one weapon at a time...

There are plenty of dual weapons in existence, just none that you can mix and match which gun is in what hand. So basically you pickup 2 smgs as one weapon, or a smg and plasma rifle as one weapon. Those exist. You cant take one of those, and go over a single plasma rifle, and expect to switch the smg out and get 2 plasma rifles.