The Children of Shadows loved using these. The very notion of bone and poison combined as a weapon; it touched some deep dark part of themselves and filled them with a malicious sort of glee.
Alas such weapons proved relatively useless in any secret campaigns against the Saradominists of Bramblemead. Certainly, they could assassinate a baker if they needed to, but against a knight it would just ping harmlessly off their armour.
Still, they made for good talking points at the secretive meetings, making enjoyably sinister table-decorations that paired well with the wine and cheeses.