[pipecrafter]

I have a pocket knife that I made several months ago from O1 - an alloy known for susceptibility to rust. However, even my in pocket while working in a hot and humid environment, it hasn't ever developed "rust". It has, however, developed a nice patina that I would expect O1 to get - like when it's given a light etch in FC. I do keep it lightly oiled as well, on the blade as well as the pivot.

I think that if I left it un-oiled and in a humid place, yes it would rust. But as long as I pay attention to it, it's never going to be an issue.

One thing I would suggest is that, if you're going to consider selling carbon steel blades, that you make, use, and test one yourself for some period of time. Even make a simple one and test it to destruction. That way you'll know the limits, as well all the subtle nuances, of your product.