I am not sure what all the talk about the preservation of this blade is about. Moro kris were not routinely acid washed like their Indonesian cousins so it does not seem surprising to me at all that a relatively well taken care of blade from the early 19th or even late 18th century would look like this.
Pepper, have you considered giving this blade a light vinegar etch to bring out the twisted core pattern? It's a rather gentle process that would not damage the blade and it would certainly look cool if that pattern stood out more.
