Hi All,
Putting on my botanical hat, the "pelet" pattern in the wood looks like fungal growth, and the english term for it is spalting
(here's the wikipedia link). Spalted wood is weaker than unspalted wood, because it has been (or is being) rotted by a fungus. The pigment changes are being produced by fungal activity, either staining the wood dark or bleaching it, depending on the species. As demonstrated here, spalting can often be so pretty that it commands a premium price.
Note that I'm talking about the underlying phenomenon that's producing the patterns, not the way they are classified. That is your forte, not mine.
Most of the fungi that produce spalting patterns are wood rotters, and unless the wood in the keris and sheath have been treated to kill the fungus, they will keep rotting away, albeit slowly in most cases. I'm not an expert on treating wood rot, but please be aware of the possibility, and check to see if the pattern changes over time. If it does, you may want to have it treated at some point.
F