5) The Black Judge sents you to Giran to Blacksmith Pushkin.

6) In Giran's Blacksmith shop talk to Pushkin and he agrees to make the manacles for you but you need to bring back some items first.
When you have the items talk to him again and the manacles will be in your QUEST inventory. Go find a Black Judge again.

7) The Black Judge will move the manacles from QUEST inventory to your regular inventory and give you some parameters for using/leveling the Sin Eater.

8) At this point you can summon the Sin Eater and exp like normal, but you will receive 0 exp for each mob you kill and the Sin Eater will take all of it. It only takes YOUR portion; if you are in a group everyone receives their normal share of exp. The Sin Eater eats wolf food pretty fast so bring a lot, you'll need to put the food in its inventory and it will eat it on its own when it is hungry, or you can feed it yourself by double clicking the food

9) When it levels up (you can check its stats by "talking" to it) bring it back to the Judge. The Judge warns you about removing items from its inventory so I suggest unsummoning it before visiting her. She will then take off a random number of PKs from your character(1 to 10) and return the manacles to you.