As its description implies, the Hunting Knife is a dagger desiged around horizontal/overhead slashes at the cost of stab's effectiveness. Due to this, you may want to equip it with a shield, as otherwise your overhead attacks will become stabs. Generally speaking, those looking for a weapon of similar preformance are redirected to the Saber, who is fast for its class and gains significant reach.
The Hunting Knife can be quite deadly against enemy Men-at-Arms and Archers, as it is one of the best weapons in the game at overwhelming opponents at extreme close range with rapid fire combo attacks. Since it attacks so quickly, you will often interrupt an opponents attack animation and leave them defenseless until the killing blow. The Man-at-Arms can use his speed and evasion to position himself for a good slash. However, the archer's mediocre speed/low defense and the weapon's short reach make it essential to know how to parry and combo effectively and consecutively.
It is the second shortest weapon in the entire game, only beaten by bare fists.