Hello Thilo,
you are also infected?
I use for cleaning a standing tube (a drain pipe from plastic, sheap to get in a do-it-youself-store, together with a fitting closing) and attach in up a wire. So you are able to hang the blade inside without the liquid have contact with the handle. As cleaning liquid I use lemon acid from the supermarket (it's here in Germany cheaper than pineapple juice and do the same job). When you control it good there is no risk for the blade and it works fast and good. Take it time by time out and pick away the rust with a hard needle. Like this I have cleaned a lot of blades with very good effort.
I agree with you that this isn't the original hilt and there have been two baca-baca. I can't say something to the origin but I am sure that Jose or Kai will be able to determine the derivation.
Regards,
Detlef