A Survival Knife will be used to hack, pry and cut.  Therefore strength
is the first thing to look for in a survival knife.  This means a fixed blade,
full tang knife.  The tang is the extension of the blade through the handle.  It
should be the full thickness of the blade and as wide as the handle all the way
through the handle.

This requirement rules out those "survival knifes" with the hollow handle that
you can buy for $7.95 at a certain chiinese tool store.  The blade on these is
soldered to the hollow handle.  There is no tang, therefore no strength.  This 
is also the problem with folding knives.

A minor decision is the material that the blade is made of - stainless or
carbon steel.  Either can make a good blade.  The difference is that one of
the striker (flint) fire starters will not work very good with a stainless
steel blade.  The carbon steel blade provides plenty of spark.  If this is a
problem buy one of the carbon steel knives.

Sawteeth on the top of the blade are nice to have when making a shelter.  They
can cut a small groove in a branch which will not allow the rope or para cord 
to slip from its position.

An adequate fingerguard is an important feature.  Without one your fingers could 
slip down onto the blade.  This could hurt.

The blade should come to a point.  The bottom side of the blade is sharpened and 
the first few inches on the top side is fashioned into a "false edge".  This is
a tapered edge that allows the blade to end in a sharp point that will allow the
knife to be used to drill holes in wood, skins, leather or bone.  Would be 
useful if you were making a fire bow.

The handle should be the last thing to look at.  It must be sturdy and comfortable
to hold.  It should not be slippery when wet or bloody from skinning an animal.

Do not forget a sturdy sheath and a sharpening stone.