All old Nightfall/trials weapons that were in Xur's loot pool pre-MoT were revamped and added back into Zavala's/Saint's pools in MoT. You can aquire them with nightfall engrams/ciphers and Trials engrams/ciphers, like pre-EoF. It's a much better system that never should've been removed in the first place, it's sad that they decided to kill the game right when they fixed everything they broke with EoF, engram focusing being one of the biggest imo. In short, you have to play fireteam/pinnacle ops and trials again to get pinnacle ops and trials gear, instead of praying they'll show up in an oversaturated loot pool every weekend, same with older comp and onslaught weapons, just like it always should've been. Xur's loot pool was way too overloaded and the chances of something good being available was next to zero, and even when a good trials/nightfall/etc weapon was available, it was always junk rolls. This system is way better, plus T4/5 versions give way better chances on decent rolls.