Go to the riverwatch camp with the fighter thrall named Ritualist. There is a chest near him/her. Beside the chest is a jaw bone. Look at the faw bone and interact with it. You will learn the recipes. It doesnt say you can interact with it when you look at it, just do it.
Have done.
Sadly the Darfari weapons are just stone weapons with some more exotic components, teeth and bones. The Darfari ‘sword’ is about the worst, and the club descent. I’d say they are not worth it because of the need to repair them over just base stone.
Wow ! I didn’t know that, I went there and indeed we can learn new recipe 
Thank you so much !