Sepuh or ipuh in a keris

[A. G. Maisey]

I'm not at home David, moving around a bit, and pressed for time.

1. Why there are different types of sepuhan in the keris?

Different makers, different times, different objectives.

2. What is the actual purpose of this "sepuhan" process in the keris making? Is it having the same purpose as "quenching" in the blade making or is there more purpose to it?

As David has said, to make the blade usable as a weapon, however, a keris is not drawn after the initial quench, the fact that it is a laminated blade and that the iron/nickel pamor does not harden during the quench protects against fracture in use. Ferric material needs to contain carbon in order to harden. Steel contains carbon, iron does not, neither does nickel.


3. Is there literally exist a "poisonous keris"?

Any non-sterile keris plunged into your guts will poison you.

I have never heard of a sterile keris.