Some new weapon changes have just been synced and take effect immediately.
New stats: Nearly all weapon stats have been updated to bring them more in line with each other. After the number of weapon fires were set to max rather than a random number, this was needed to ensure that some weapons (such as the flamethrower, most notably) were not particularly overpowered or underpowered. Damage values, number of hits, and range has been adjusted for most weapons. This also takes into account the other new feature synced over, which is..
Dual wielding: Many weapons can now be dual wielded. These are noted by the "Dual Wielded: Yes" tag on the projectile and non-projectile weapons rules. You may only dual wield two weapons of the same kind, and both weapons should now fire in combat together. There is a penalty in the form of 50% of your normal hit chance and 50% of your normal damage for the "off hand" weapon (one of the two; does not matter as both weapons must be identical).
Shields are not currently implemented, but may later offer a nice alternative to dual wielding when you desire increased defense over enhanced offensive power.
As always, any of these stats and modifiers may be adjusted if they are deemed too weak or too powerful. Please report any bugs you encounter to the bug base.
Syn Edit: Some additional notes to address some of the questions that have come up-- Heavy weapons (e.g. rocket launcher) do currently seem underpowered compared to other weapons. To my knowledge this is because they will be intended to target hull, rather than player HP values, so this is a matter of their not being fully implemented. NPC shop weapons may not have been properly updated and this will be looked into and adjusted. Thrown weapons are also not fully implemented, so at the moment these changes primarily apply to PW/NPW.