The Ice Daggers are two daggers made out of ice and are held similarly to Mileena's/Li Mei's Sai. They are used by Frost in Mortal Kombat: Deadly Alliance, Mortal Kombat: Unchained, and Mortal Kombat: Armageddon.
Sub-Zero also uses the Ice Daggers in his Cryomancer variation in Mortal Kombat X, though, unlike Frost, his Ice Daggers have a much smaller presence in his moveset, appearing only in one of his special moves. The weapon is also seen in Sub-Zero's gear in Injustice 2.
The daggers are created by Frost's ability to control the ice element. Due to the fact her power over ice is inferior to Sub-Zero's, the daggers are the full extent of her ability to form solid objects, while Sub-Zero is capable of creating larger objects such as a sword.
In Mortal Kombat X, Sub-Zero uses the Ice Daggers to deliver quick, precise, and deadly strikes to his opponents during his Polar Puncture special move and Pick Your Brain Brutality. Sub-Zero's daggers also appear smaller and less serrated than Frost's.
In the mobile version of Mortal Kombat, the Ice Daggers are a Equipment Kard. It increases the damage of basic attacks. When equipped on Sub-Zero, it gives him a chance to convert half of damage of Special 2 to his own health. In fusion Tier X, it also increases by half the chance of critical hit against a frozen enemy.