The rust test results after the first few dives is poor. There is apparently spots of carbon from the steel forging process that allows spots of rust to easily start.
I would not brag about this knifes rust resistance at all, but with lube, care, and upkeep...it is a usable and cheap alternative to some of the $50+ knives that I couldn't justify purchasing as a new diver, and if you lose it, which I almost did on dive #4, the tears won't flow quite as much.
I was impressed with its large blade performance when a co-diver requested me to tie a 3/4" braided rope to an anchor line at 100ft. The rope end was a bit frayed, and it wouldn't tie well. I decided that my first use of a knive underwater would be to whack a clean end on this rope. This knife easily did that. I don't think that event would have been as impressive with the 3" bladed 2nd knife.
Good luck