Its a spring loaded knife blade, you push the blade in and its caught with a button catch, push the button and it releases the blade and shoots out the front.
Do you possibly mean a knife that is attached to the front of a rifle? If so, that is a bayonet.
Scrape it with a knife.
I have used the Work Sharp Knife and Tool Sharpener for all kinds of knives.
to have a weapon or to have a knife that is pocket size but can still work
A round knife is a knife used to work with leather. It has an axe-like rounded blade that cuts leather with a rolling action of the sharp edge.
Fork on left and knife on right. If you have lots of courses you work from the inside to the outside. You would have a smaller fork for starter then work outside for the rest.
Eat with fork and knife or eat little bites
This feature allows the knife to be mounted left or right handed.
spear, machete, obsidian knife, maybe pocket knife (if the pocket knife doesn't work then the boar wont hurt you)
super jump off a curved object and have your frind stand in front of you than knife and pull out your throwing knife without throwing it
This is probably a bayonet, a knife attached to a rifle, spear, etc. which in effect turns it into a spear, good for fighting at close quarters.
sure, will work well