Information doesn't have literal weight, but if it did, Ubisoft would have posted a metric ton of it about The Division 2's weapon mechanics. The highlights are a new rifle type, unique Exotics that fit with the story and reworked talents.
The Division had plenty of weapon categories already - pistols, SMGs, shotguns, assault rifles, LMGs and sniper rifles. Another one will be added in The Division 2, simply named rifles. The way Ubisoft described them, these will be weapons previously found in assault rifle and sniper rifle categories but didn't fit either very well.
Rifles will include semi automatic and burst fire weapons such as SCAR-H, M14 and FN FAL, while sniper rifles will apparently only be the bolt action weapons while assault rifles will be automatic fire only. These "regular" rifles needed a separate inherent talent to balance them out, according to Ubisoft and Massive Entertainment, which they will have now.
As far as Exotics go, The Division had plenty of them but mere few were distinct and even fewer were useful. Sure, we all love The House, Bullfrog and Big Alejandro but let's face it - none of us ever took Cassidy seriously and even the dual Cassidy Lone Star build was considered a fun one, rather than serious.
The Division 2 will aim to rectify this, as the appearances of Exotics will be unique and "clearly distinguishable". More importantly, it was announced that each Exotic will have its place in the world, hopefully meaning that we won't roll our eyes when one drops the way we did if we got a Damascus at the end of a Legendary Mission.
Weapon talents have been reworked from ground up in The Division 2 and will have two types of requirements - minimum and maximum stats. Therefore, we can forget about stacking stats like Stamina for Predator's Mark or Firearms for glass cannon DeadEye builds.
Some weapon talents were sometimes hard to spot, for example it was a chore to keep track of when The House's damage bonus would kick in, so The Division 2 will have a partial fix for that too. When aiming down sights, an "augmented reality" tracker will pop up that will help us keep track of how many bullets we have until a weapon talent activates and it will light up when the talent is actually active.
Another interesting bit of information is about grenades. We will no longer be able to carry bajillion grenades like before, as there will be only three types in The Division 2 - Flashbang, Incendiary and Frag Grenades. Each of them will be tied to a specialization - Sharpshooter, Demolitionist and Survivalist, respectively.
We picked out the few details we considered the most interesting for the sake of not writing a wall of text, but if you're keen on dissecting every bit of information about The Division 2, you can head to the official website and check all the announced changes to weapons and their talens.