Hello Russel,
nice piece. I'm a rank amateur at this stuff so can't help with i.d. and age etc. But I think Mr. Maisey posted recently on updated cleaning methods he uses for cleaning keris. He mentioned that the Golden Circle Pineapple Juice used to be his cleaning solution of choice but due to a recipe change of the product he has now switched to a vinegar solution.
I'd recommend searching for vinegar de-rusting posts and seeing if vinegar might be applicable to your item.
http://www.vikingsword.com/vb/showthread.php?t=15923.
best wishes