I recently acquired the treasure hunter passive, and I was under the impression that it would increase the quality of items in chests and safeboxes. I still get greens from safeboxes... is something messed up? I have my legerdemain skill at 20.
The Treasure Hunter Passive only works on chests in the world, not safeboxes. Furthermore, you will still receive green items from Simple chests.
With the Treasure Hunter passive, you should receive blue/purple items from intermediate and above. Intermediate chests drop 1 non-set blue and 1 blue set piece all of the time with the passive active.