My background is in the aerospace industry where I worked for 35 years.  I can't help but think of three metals that conceivably could be used in knife fabrication.  For the blades, has anyone made them out of 300M heat treated to 280,000 psi?  It is an expensive steel that has terrific strength but also has good ductility. It is used a lot in the places of the plane that have high stresses and a small space to put it into.  Usually steels heat treated to 280,000 psi are brittle, and would not be a good choice.  One problem with 300M would be corrosion, so the blade might need to be plated.  I think the advantage would be an edge that would keep its sharpness a very long time.

The cadillac of aerospace steels is called MP35N.  You can heat treat it to about the same level as 300M and is also ductile.  But it's real advantage is it is a stainless steel.  This stuff is amazing, but very costly.  It has cobalt in it, thus raising the price.  But you wouldn't have to face about corrosion issue.  Again this would hold an edge very well.

Lastly I can't help but think of magnesium for other parts of the knife.  Magnesium has the highest strength to weight ratio than just about any other metals including aluminum.  This stuff is amazing also.  You pick it up and it feels like a feather, and yet it has impressive strength characteristics.  It could be used to make a super lightweight knife.  Two problems would exsist however.  One would be corrosion; it corrodes fairly easily.  The other would be ignition/burning.  If the metal was hot and a spark contacted it, it might ignite.  And if it does it is nasty; very hot fire.  The only way to put out a magnesium fire is to simply let it burn itself out.  But I think it would work as long as it stayed away from the campfire.  I know of a certain bomber that has a major brake component made out of magnesium, and it has been used successfully for more than 50 years.  It is banned from commercial aircraft because of the burning issue.

I wrote these "out of the box" ideas just because I thought you might find it interesting.  Feel free to comment and/or call me an idiot.