ref a bushcraft knife, it is normally carbon steel for 2 reasons 1) it holds an edge better than stainless (on the whole, some exotic steels differ but that effects price) 2) carbon steel can be struck to form a spark for making fire...
the full tang because its stronger and 3-4 mm thick for the same reason, this is to allow for battening wood down to make a fire, a bushcraft knife is often used for this...
a scandi grind normally because it acts as a wedge when spliting wood and is a robust edge rather say than a fully flat grind which can be damaged more easily than a scandi.
however this is not to say a full flat cant be used or a thinner blade, it all depends of what you like to work with, what tasks your going to use it for and how much stick your going to punish it with...
for me a mora clipper is good enough for everything, even battening which it takes in its stride, but i much prefer a thicker blade of 3mm with a flandi grind, O1, not scandi but not full flat, more a place in between, this gives a robust blade but makes it better for carving jobs....
the handle and sheath is totally a personal thing wood is just as good as plastic or resin and does have some advantages and likewise with plastic etc...
basically its what you like to use and what you can afford, the rest is