For me a problem to accept Madura smiths as initial propagators of twistcore on Philippine blades is, as I wrote, the lack of other more elaborate patterns. We see only twistcore with exeption of some very rare Adeg patterns.
I also doubt, there are Madura blades at all, which have rows of more then 3 twistcore stripes, seen on Kampilan and sometimes on Kris. Yet the normal keris blades are much narrower, of course.
Here is a thread about a twistcore Yataghan in SEA dress:
http://www.vikingsword.com/vb/showthread.php?t=7622
Here is a thread about twistcore Mandau:
http://www.vikingsword.com/vb/showth...4243&highlight
Also pictures of a Kampilan and two Yataghans, one of them (the upper one) dated 1592.
Regarding Sendai Keris, I have the same picture, the best available at the moment. The keris is out of stain, has a polished and in some areas slightly rusted surface, so it is difficult to be judged and no categorical statements can be made. Yet I would say, there is at least a possibility of a pattern welded Pamor Miring, even if the Pamor material isn't of high contrast.