Well, Alan is, of course right. This is not a keris. Nor do i believe this interesting and beautiful dagger was adapted from a keris. So i am tempt to send it over to Ethno as we only discuss keris on this side.
BTW, i do not see anything that resembles a mendak. It does have a feature that might be called a selut on the base of the hilt. And that strange guard is like nothing you find on a keris.