So, Wowhead did a coverage of the Netherlight Crucible which progresses your artifact in 7.3. From what I've gathered, the rundown of it is you need to clear up to the third area of Argus to unlock it. It kind of seems to work like a talent tree that unlocks various traits which can up your artifact's item level by 5 up to 15 (so 3 points), as well as points you can put in which give you stats and procs for your abilities. The third was kind of confusing to me with the way it was worded, but it looks like it allows you to upgrade up to three traits, whether this allows you to put a second point into a one point trait or an additional point in the current four point traits, I'm not sure.
Link to the article with better explained and more in-depth information: http://www.wowhead.com/news=268045/n...n-in-patch-7-3
I'm kind of curious about which path each spec would want to go, specifically for Fury. I was thinking the Holy path would be nice to go into for the additional 650 Haste but the Concordance effect looks like it would be pretty shit with the Crit. Maybe it'd be worth going through Shadow for the Mastery and Vers for Concordance?
As for the traits, I think it'd be pretty obvious which ones we'd upgrade regarding traits for Fury.