An interesting kris probably from Lombok, the hilt depicts a demon which may be Ravana. The blade would benefit from warangan treating indeed, the ivory warangka in kekandikan style is discolored on the back side because the maker used the outer surface of the tusk. I would estimate the age to first half of 20th century but the hilt is probably more recent.
PS: The top part of the warangka may be from bone (the pics are not clear).