I'm glad you brought this topic up, Empu Kumis.
I have noticed these keris for a couple of years now and have wondered about them. The hilts seem bronze, but the blades steel. Bronze does not "rust" oxidize in the red/orange/brown colors like iron. My only problem with these is what Nechesh has raised in that there is not any information, research, or provenance associated. I have looked and have found nothing. Until I do, I am always wary (I also don't get anything I have not researched).