Exotic/Legendary weapons owned, worth upgrading?

Atheon's epilogue is an absolute must for PvE and Raids. It's also a decent PvP auto rifle. The void damage on a primary makes it stand out, and the fact that it's legendary means you can save your exotic for another slot. So for your primary, I'd focus on upgrading this first. In fact, out of all your weapons, do this one first. Patience and Time seems really good. Invective (and shotguns in general) wreck in PvP, so you definitely want to have one of those handy and upgraded. For your Heavy slot, I'd recommend any legendary rocket/machine gun. This is because in PvP, a rocket will kill almost no matter what (if you don't miss), and you don't get to use it that often, so it's not worth taking up your exotic slot. Level up one of each type of heavy so you can swap between them for different situations. Just pick your favorites for this one. Bounties are a good way to level up weapons, and before turning them in I always swap out any that are already max XP so I can boost weaker weapons. I haven't ever dismantled legendary/exotic weapons unless they're duplicates because I feel like some may be useful in future situations (such as an element burn modifier on a nightfall). As far as finding more ascendant materials, good luck. Suros Regime (exotic)/Shadow Price (legendary) are my go to auto rifles, which I swap when I need an exotic in another slot. Thorn is surprisingly useful in PvP as well. I want to fully upgrade my Invective shotgun when it levels up along with my Icebreaker, which is great for PvE.