After holidays and all, I finally got around to identifying the coin utilised for the guard. Numismatics is obviously not my forte and it took awhile to sort out some misconceptions of mine...
Long story short, this is a late 19th century copper alloy coin from the Guang Xu reign which was produced in Guangdong Mint (at that time just outside of Canton town) sometime from 1890 to 1899 (BTW, that's Manchu script on the reverse side). According to two Chinese coin collectors, this well-patinated example is in very good shape and it was probably removed from circulation soon after it was minted. Thus, it stands to reason that this coin was utilised already around of the turn of the 19th century for this Badik Lombok and has been with it since. So although the coin itself has not a high value, it's at least not a fake coin flippantly used to dress up a fantasy dagger but rather a traditional Sasak style...
I'm not sure wether this has any relevance regarding the age of the wooden fittings which, as always, may be not as old. However, I'm confident that both, warangka and danganan (ukiran), are both genuinely crafted pieces and at least of vintage age.
Regards,
Kai