If you're talking Aeonic weapons, you have to clear RoV to get access to the goblins that start it, and then you need something like 52000 beads for the next step, and so on and so on. Ultimate weapons.

If you're talking some of the non-Aeonics, a bunch were released for the new Unity fights (Khimaira/Cerberus/Hydra remakes), as well as for T2 Reisenjima Gaes Fete NMs.

And if you're talking older gear besides the stuff introduced this patch, they're spread among things like Delve, Unity, Incursion, Vagary, and other Gaes Fete fights. I suggest you go to BGwiki and do some research; it'll save you some time.