Hi Conduit. This is a topic which has been discussed many times on this forum. Rather than start another thread that simply repeats the same information i would recommend you try various key words and search our archives for threads that have discussed this topic before.
There is one thread in our "Classic" section in the Sticky threads at the top of the forum page about this, but unfortunately a glitch in the system lost a great deal of the old forum threads some years back. But thanks to the Wayback Machine i have found a link to it. This will get you started, but again, using various key words related to cleaning and staining keris your will find many threads related to the subject. Try words like "Cleaning keris" "Staining Keris" "Warangan" and so on.
https://web.archive.org/web/20160703...ML/000717.html