I had this too, but can't remember where I picked it up. Was it in the Goblin Camp?
It's from the Owlbear and the dead dwarf (The one that's on the path between the Grove and the Owlbear Cave).
Owlbear mom has the spear head and the dead dwarf has the shaft.
Highlighting that the dwarf was using the spear and it broke during an encounter with the Owlbear.
