Many thanks to everybody for the very informative comments!
David: the letter is B. 66 can be the year of the handle manufacture
Kai: I have bought the Kris in a very rusty and neglected condition. I am reluctant to polish it any further. It has laminations running along the blade (snakelike, like on Keris), but very low contrast and definitely no twisted core. You can see it on the picture of the tip.