I am a fine of the Century line as well. So far I only have the Endeavour. I also have no idea what steel was used but I've noticed a few things when comparing them to today's SAKs.
1) Steel - The steel seems a little softer on the Century. Mine now has a small crimp along the final 1/4" to the tip thanks to what I consider very light use. I know I've used my other SAKs and Camillus harder. That being said, I was prying with a knife blade so shame on me.
2) Logo - The logo on the scale seems to only be screen printed onto the plastic. As such, it is very susceptible to pocket and handling wear. I've worn several other SAKs but never as fast as with my Endeavour.
These observations don't make the Century line less than Wenger, Vic, or others. Just personal experience. I still like them very much. Unfortunately even when they were available new they were priced higher than the well known and respected Vics and Wengers.