[Gustav]

I agree, Sampir could have had agressive sanding. I cannot recognise it as antique by details of carving (and/or patina).

Hilt cup is close to an old form, of which I too have seen some examples.

Regarding Gonjo - I also am not particularly interested in Keris from South Sulawesi, or, as it might be with this Keris, perhaps even "Tangguh Kupang", but the examples I have seen so far normally don't have Gonjo made from differently looking material.
One more detail - Jenggot has a comparatively well preserved Dha. It is normal even for this kind of Keris to have similarly carved Dha on Rondha Nunut and Greneng. Dha on Rondha Nunut is quite eroded, we actually see only the very bottom of it (if there is something from original Dha left at all)- so definitely material has been lost at Wadidang.
In that case Greneng on Gonjo is not simply eroded, it is made to match the already eroded Dha of Rondha Nunut - or Dha on RN was recut together with the Dha on Gonjo.