The Ballistic Knife is available in the shop for purchase. You can buy 5 of them for 1600 cash.
"Agile device that throws blades at high speeds that can kill enemies in a single shot when properly aimed."
When used, the ballistic knife is shot forward at a high speed. It does a lot of damage and can one shot an enemy if it headshot. However, it has a short range. The ballistic knife is most effectively used if you are being attacked by an enemy that is very close to you and you are close to dying. You should equip the ballistic knife if you are using a sniper or another slow firing weapon.