A Plastic Keris? for comment.

[knife7knut]

One of the easiest ways to test an object is to find a smooth spot and rub it briskly with your finger several times and then either sniff it or touch the tip of your tongue to the area.Styrene plastic not only gives off an odor(compare it by doing the same to a plastic model car)but will give a burning sensation to your tongue.
Celluloid(an early type of plastic made with cellulose nitrate,camphor,and alcohol)will give off a vaguely medicine type smell.Bakelite(another early plastic)gives off a very strong smell.Resins are probably similar to styrene(not too familiar with them).
If it is found to be made from celluloid,it should be isolated from other knives as when celluloid breaks down it gives off an extremely corrosive gas that will rust carbon steel very quickly.
I've had this problem with vintage pocket knives and it seems to occur at random.I've had several knives that had the scale on one side crumble and fall apart while the other side remained as new.No one seems to know exactly what triggers the reaction,but when it does the process is irreversible.
Just my two cents' worth.
Cheers
Ray