It functions identically to the one from Path of Glouphrie, but can be equipped in the main hand and off-hand slot, saving you an inventory space at the expense of being unable to attack. Unlike the other crystal tools, it does not degrade as you use it, nor does it have any impact on Shattered Heart rocks[1]. However, if you die and don't protect it, it turns into the crystal tool seed at your gravestone.
When added to the tool belt, a crystal tool seed is returned to your inventory.