Awnya N'Kval <Najena's Elemental Jeweler> sells upgrades to Ward of Elements Jewelry.

Located on the Lava Storm Docks. 

To upgrade an item,  you will need the corresponding T2 Shard item, the drop from Ward of Elements and 1p 50g.

With the exception of Symbols, bucklers and tower shields, most jewelry can be used by any class.