Hello Alan,
That's the usual construction with a high-carbon steel for a good cutting edge sandwiched between more ductible steel/iron for making the sword less brittle. The latter often shows more extensive lamination or twist core pattern. Can you post a close-up from the base of the blade so that we can see the pattern better? From your angled shot I was guessing at twist core but your current pics look more like lamination parallel to the swords plane (called pamor mlumah on Java).
The spot at the tip is most likely silver which usually gets a golden patina from fruit acids - see this thread:
http://www.vikingsword.com/vb/showthread.php?t=1243
Don't soak your sword as not to overdo the etching. The glittering you're seeing is the metal structure rather than some fancy metals in an alloy or pamor.
Regards,
Kai