Less duplicates when opening Legendary chests and accessing the Library of Esoteric Artifacts. Or if you do get duplicates, you don’t lose a Skeleton Key or a Fragment of Power.
One player I played with thought that each chest had a different percentage of chance for a specific weapon 
. From what I noticed, he might have been right 
.
Try to open 
various chests @Trappist01x , especially those that you haven’t seen for a long time.
Regarding the library, repetition is indeed annoying. From what I understand, getting the same recipes 
was meant to encourage players to trade and exchange. And it really worked on our PvE-Conflict server.
I would definitely like to see more legendary items and recipes 
- increasing their number will also reduce duplicates 
.
Maybe it would be nice to make Archivist repurchase extra scrolls. Maybe give one Fragment of Power for 5 of them and maybe give some random reward just like goods we occasionally loot from Bearers.
Maybe a merchant at Sep. City where you can get gold for each (1 bar?)
It would be nice too. Extra scrolls are useless in SP and in low-populated servers.
SP in general should have its own rule set… less connection to online patches. the need patch build-able zones shouldve been online only thing. Or high health counts, or repeat items.
Chest drop rate… from my “collecter” / 100% character, no matter chest, certain ones seem higher to drop. I have few chest on her, that just have way to many of certain ones. I tend to do round world clear for keys and chests.