From Joe Talmadge's steel FAQ:
"Titanium Newer titanium alloys can be hardened near 50 Rc, and at that hardness seem to take something approaching a useful edge. It is extremely rust-resistant, and is non-magnetic. Popular as expensive dive knives these days, because the SEALs use it as their knife when working around magnetic-detonated mines. Mission knives uses titanium. Tygrys makes a knife with a steel edge sandwiched by titanium."
50 Rc is typically way too low for a working knife. While titanium has some advantages in certain situation I would never want one for most tasks. The advantages of titanium in folding knives, as part of the liner or handle mechanism, are strength and weight. While not necessarily good at edge holding titanium is difficult to bend or shear and is extremely light while imparting additional strength to the folding knife, hence, its use as a liner or handle material. Chris Reeve Sebenzas are among the strongest folding knives made due to the solid titanium handles and integral locking mechanism. They are also very light and fast.