You can stop wondering how you can upgrade your Legion Legendary items in World of Warcraft, because Blizzard offered the solution. Players will be able to turn their 910 Legendary item into a 940, but they will need to work for that. Once the Nighthold raid opens (on January 17th in North America and on January 18th in Europe), players will find a quest in Dalaran that will help them upgrade their Legendary.
This quest involves collecting a number of Essences of Aman’thul, which can be found in Nighthold Raid Bosses, Weekly Mythic Keystone Cache, Emissary Bags, and PvP Weekly Quests. Once the quest completed, you will be rewarded with a Distilled Titan Essence which helps you upgrade your Legion Legendary item. You will be pleased to find out
that once the Nighhold raid opens, any new Legendaries that you discover will already be iteme level 940.