Knife history: Drawing Blood Lore
Just as with swords, regional and cultural superstitions exist regarding the treatment of knives that are used in combat. One common superstition states that it is bad luck to return a combat knife from its sheath without using it to draw blood. A Scottish myth exists surrounding drawing the sgian dubh (Dirk), without drawing the blood of an Englishman. These superstitions are usually attempts to insult the culture of the enemy.
There are cultures that believe a knife does not belong to an individual until it has 'bit' them, or tasted their blood. After initial blood letting the owner and the knife are bound in their destiny. Practitioner in these superstitions may intentionally prick their finger on the blade of a knife rather than wait for an accidental cut. The knife will stay sharp longer and is less likely to accidentally cut its owner once it has tasted his or her blood.
This blood drawing has made it's way into our classic science fiction. Dune Writer Frank Herbert invented the Fremen and the Crysknife. Once a Fremen warrior unsheathed his blade it must draw blood before it is sheathed.