In my experience, non-scouring Brillo pads and liberal WD-40 work very well. Bit smelly, but the results are instantaneous and there is no danger of damage to vulnerable parts and no concern about possible interactions with the blade. I suspect the mandau was patinated, and the patina was lost too...
This electrochemical method looks more suitable to semi-industrial uses.
Also, knowing my cats, I am a bit leery of finding one or both of them de-haired
