Ice Blades are traps in Ocarina of Time. They are found exclusively in the Ice Cavern.
These stationary traps consist of two blades that will continuously rotate in a counter-clockwise fashion around an open room. These traps cannot be defeated and will cause harm to Link if he is hit by the rotating blades. Link is able to avoid the blade attacks by holding his Shield and crouching down, in which the blades will pass right over his head. The blades do move slow enough where Link can avoid them if he is constantly moving in the same direction that the blades are rotating. However, as they are found in rooms with ice, it's often difficult for Link to keep his balance.
Very similar traps known as Whirling Scythes are encountered in the Shadow Temple.