nef
A sheath
A knife 'sheath' is a leather cover in which the knife is kept and worn on a belt.
Grotto
a sheath
Zarf. It's an ornamental metal cup-shaped holder.
Floss holder and dental floss sticks come in either a "knife" shape or a "Y"shape.
A teapoy
A Boot Knife
A machete is a broad heavy knife.
cobb
There is no throwing knife in Call of Duty 4: Modern Warfare.