Historical and reenactment daggers, viking seax (scramasax), dirks and stiletto from Hanwei and Legacy Arms
A Seax or Scramaseax is a dark age knife which has a single edge, a straight back and a clipped point. Examples of which range from a few inches a few feet long. They were used both as tools and as weapons thought the 3rd - 11th century.
A dirk is a type of dagger. The best way to think of it is as being "a dagger in the Scottish fashion." Although other nations and cultures use blades called dirks, its main attribute is its cultural ties to Scotland, since that's where the style originated.
A Dagger is a knife with a very sharp point designed or capable of being used as a thrusting or stabbing weapon
A stiletto (Italian: [stiˈletto]) is a knife or dagger with a long slender blade and needle-like point, primarily intended as a stabbing weapon.