Level 35 - 37 shadows drop this item, any class that can solo one of these can get the item at whatever level they can solo them at. For example, a level 44+ cleric can easily solo them, and pet classes can do so earlier.
A lvl 44 cleric could probably solo a shadow, and the shadows do in fact drop these (I got mine off of one today in fact :) ). However, the cleric (or whoever) will have an extremely hard time soloing merely because it's virtually impossible to single pull in here without someone else to break up the spawn. So unless your lvl 44 cleric can solo a shadow and two lvl 39 golems, don't count on being able to waltz in and pick one up too easily. By the way, I fought here for three or four full days, and I have seen drop so far: one trance stick, two wraithbone hammers, and this bad boy. So they aren't too terribly common.