ok, just listen and learn
As Chainer said, it wasnt the Sin Eater itself.
When u do the quest, u lvl the sin eater, etc And when ur pk's drop to 0 again, u dont lose it, instead, the black judge handles u a manacle, and that can be traded and sold. That is not the sin eater, its just a normal item. If u pk more and wanna clean them, u can go to the black judge again and u'll skip the part of the quest where u must go to sea of spores, to the blacksmith, get all those molds and mats, cos they are to make the manacles, which this time u will already have
