Hello Johan,
According to the book "Keris dan senjata pusaka bahari", your warangka is in perahu labuh ( a type of boat it would seem) style from Cirebon. The S shaped rib on the right side of your picture is an additional indicator besides the slightly curved ends. By the way the pendok (metal oversheath) seems inverted, the carved side should be on the front of the scabbard.
Your warangka seems to be made from kemuning from the pics but other options are possible, a better picture would help.
Regards
