You have beaten the vicious Monk at dice claim your reward at the GOG.com website?
 

I got this message within the game but I can't find any rewards on GOG.com anyone know what all that is about?

The (item DLC) reward was already included in one of the early patches to the game, along with all other DLC.

Edit: Hmm I was almost certain that this was the case but Google is telling me that it was a GOG promotion (some discount for GOG purchases) I guess it already expired by the time I got around to playing the game and I assumed it was DLC… Oh well…