All items on the Eternal Realm were turned into Legacy items due to all the changes with the itemization overhaul. You will be unable to use the new systems on these items and they are locked in terms of their stats. You will have to find brand new items moving forward that will be even more powerful than your Legacy gear.
You can still wear those items mind you, until you find something better, but they can’t be altered in anyway.
If you want a brief summary of the changes:
Would also suggest reading the patch notes, and the news section regarding all the changes, such as the new tempering, master working, etc.
If you have more questions afterward feel free to ask.