Whatever it is... keris is made by humans and for humans... period.
I've seen a picture of an example of what Newsteel had mentioned.
When looking at the blade of such 'extraction'... it seems new... probably Maduran-made. These pieces is, probably imbued by someone whom is well-versed in the mystic arts. A 'clever way' of ridding some of these hard-to-sell... 'tourist-class' blades.
There are true cases, but these are rare and far between.