Just ask the doorman the location of NPC, in a room.

Stormwind remembers being next to the canal.

All equipment in the whole body can be upgraded, as long as the item level is higher than the system setting.

The weapon slot is an ordinary gem slot. Gems made by jewelry processing professionals can be inlaid to obtain additional attributes.

For example, if you insert a red/orange or purple gem into the red groove of the staff, you can trigger the groove reward to gain an additional 60 points of intelligence.

But if you insert gems of other colors, you can enjoy the attributes provided by gems, but this extra 60 intelligence is gone.

If it's a dye bath, you can only insert dye gems, and you need to complete Edward the Black Prince's task to get it.