For SK go and see Squire Gristle hail him and when he asks if you have your symbol say no. He will then give you a note to take to "The Task Master", the task master is near the exit to the Field of Bone and has frogloc slaves so be careful if you are very low level as they will kill you. They are green by level 5.

Hail the Taskmaster and give him the note. He will give you a book, read the book as it adds background to the quest. Then ask the Taskmaster for "The Hammer of Exoneration" and "Please may i have the bag". You should end up with a Very heavy hammer that when used procs to produce shattered bones and a bag. The hammer is the only way to get the bones, normal bone chips don't work. Any mob that the hammer procs on will give shattered bones. 

Next go find the Mortician  loc 165 664 in West Cabilis and get a Mortac and Pestle that you must combine crushed bones in to get ground bones. "a Mortician" is a skelington and is found in a building near the entrance to the tunnels that lead between West and East Cabilis.

Fill all but one slot in the bag with crushed bones, the other needs Blood Water. Blood Water can be purchased from at least one merchant in the buildings by the Field of Bone to East Cabilis Zone. Press combine and give to your Guild Representative, it must be the NPC who gave you the quest.

You should now have your Khukri back (if you are a SK) and be ready to do the Knaves Khukri quest. Other classes will have there own item, shackle for monk and so on.