My dive knife is made out of titanium.
pros for titanium in a dive knife: corrsion resistance (very good!) and strength (havn't really tested this).

cons: Pretty expensive

It just occured to me that i have never see a folding knife with titanium blade. other than the price, what are the other reasons for this? i don't know much about steels and knife materials so i could be missing the obvious. a quick web search didn't reveal much:/