I believe that your knife is a Pacific Cutlery International Series Model 139 if the blade style is a "Weehawk"
The reason I say this is that I don't remember the Interantional Series being offerd in any blade styles but the Weehawk, the Tanto and the Utility. I could be mistaken in this but I don't believe so.
Check the link below for the International Series Models.
http://members.nbci.com/_XMCM/Ken_M.1/PC_International.htm
As for the type of blade steel, I have been told that the blade steel was made from 420C stainless.
It is not a bad steel, but not up to the standard of the Sandvik 12C27 used in the Mod 42's or the 440C that was used in most of the older "Custom Models"
The hardness of the steel varies from knife to knife as the heat treatment was not very consistant.
For the most part the blades I have checked with a Rockwell hardness tester have run from as low as 45 to as high as 55 Rc with around 50 to 52 Rc being the norm.
The one thing that I can tell you is that if you drop the blade on a very hard surface, it is more likely to dent or bend than to break.
The handles are indeed Zymak as Chuck has earlier said, which is a low temperture zinc based alloy and then flashed nickel plated.
Zymak tend to be brittle and the handles are known to crack where the blade is pinned to the handles.
The blade pins are far better then the pins of the Jaguars bali's
All things considered a pretty good knife.
ChuckG
(Not Gollnick)