Speaking of the dangerous method of staining - while searching for something completely different I stumbled upon realgar wine -
https://en.wikipedia.org/wiki/Realgar_wine
Which leads to a couple of questions.
Since when did Javanese start to stain the blades with a solution which has realgar as a part of it? Are there other cultures, which did use it on blades around 1300-1400?
If I read, that in China it POSSIBLY was used as "protection against disease, snakes, and evil spirits", so it would have apotropaic qualities - is there some kind of account about similar apotropaic qualities of realgar on Java?
Edit: here a source for use of realgar in China, which indeed mentions its apotropaic quality:
https://de.scribd.com/document/54137...-and-Tradition