I had this drop from a goblin depredator in Frontier Mountains on the Vaniki server. Magelo suggests it can also drop from a goblin taskmaster in both FM and Droga. Guessing it's a Droga/FM 1.0 thing like the Sainy's Singing Dagger.
[Sun Jul 03 16:55:49 2022] --You have looted a Goblin Stone Dagger from a goblin depredator's corpse.--