Here are some additional close ups regarding your questions on material, design and if the blade has been reshaped
(quite possible because this is not the traditional blade shape for this knife but a early/mid 20th C version).
Thanks for the pics! I've seen the blade shape varying quite a bit with these - are you going to etch it?
On it's use, in all references I have read it is described specifically as a knife for betel nuts.
Maybe it had some status implications to have a separate knife solely for this?
Yes, like I surmised earlier, it is quite possible that this was only used for this purpose by the upper strata of society. Not much else they are needing a knife for on a regular basis...
BTW, I've been traveling with a heavy betel user in another culture - the supply was coming ready to use from street vendors with not much to prepare. Does anybody know the traditional routine in Aceh when chewing betel in a social setting?