The chest in question is in Grymforge, located by the three mimic chests. I believe you have to pass a perception test to find it? It's odd. Basically, it looks like a mini-chest that you click on, which makes another regular size chest appear. If I recall correctly, that is.
Then you can either open it with skill or use the light spell.
Ok... SO it's the SAME harpist chest I already found and just lockpicked.
I was kinda hoping for some other juicy secret.
