This year, the Yule festival has quests that reward essence items.
There is a daily repeatable quest In the Spirit of Yule that requires you to do any 10 Yule quests. (Be sure to pick up the quest from Mara Sandydowns before turning in any of the Yule quests.) It rewards a Pouch of Shadow Essence Fragments. So far, I've gotten 1 or 2 Fragments of a Shadow Essence and an occasional Scrap of an Essence Reclamation Scroll. Both are bound to character and can be bartered. 4 Fragments of a Shadow Essence will get you a Festive Shadow Essence Box, which is Bound to Account and contains your choice of an Empowered Shadow Essence. 3 Scraps of an Essence Reclamation Scroll will get you an Essence Reclamation Scroll, which is not bound. If you have or will have level cap characters, you can earn the essence boxes on any character, even low level ones, and pass them to characters that can use them. Essence Reclamation Scrolls can be passed, traded or sold.
There is another quest A Festive Flurry (Intro) that requires you to do In the Spirit of Yule 5 times. There are four tiers of A Festive Flurry, requiring 20 days to complete the final tier. Each tier gives you a few more Scraps or Fragments. Last year, the tiers were not carried forward to the encore of the Yule festival.
The bottom line is that you can get valuable essence items by doing 10 Yule quests a day for any level character. Level cap characters will be able to take direct advantage, but other characters may be able to save them or pass them to other characters on your account, or sell them on AH. Essence Reclamation Scrolls have been 80g-100g recently.