I’m sorry If I misunderstood what was being said but I have to say that I have heard people say that the Indonesian Keris is an Islamic Weapon too, so I was eager to clear that up because I really don’t believe that.
About Silat its not recent but If you want to discuss that I don’t think this is the correct place to do that. There are lots of Martial arts forums where you could do that, I think you may know of one
If you take everything into account you will now see that the Keris blade symbolises the interaction of two opposite forces, the creative and destructive, the Male and Female,
The blade waves back and forth between these two opposite poles a bit like a battle taking place one trying to overcome the other. This is what my research has lead me to personally believe but I accept that lots has been lost over time. If anyone else has any other Idea about what it symbolically represents I would love to hear it.