Hello Charles,
very interesting spear head, it seems that we have sometimes the same desire, I was bidding also.
I think that this spear head is either from the North of Sumatra (Batak?) or from the Dayak, I only know items from them with this kind of talismanic inscriptions. When I have to commit myself I would go for Batak because of the ferrule. And yes, I know, both are not islamic.
Regards,
Detlef