Flying Knife

Type	Weapon
Damage	40 (Melee)
Knockback	4.5 (Average)
Critical chance	4%
Use time	15 (Very fast)
Velocity	17
Tooltip	Throws a controllable flying knife
Rarity
Sell	8 GC
Research	1 required
Use

Desktop/Console/Mobile-Only Content: This information applies only to the Desktop, Console, and Mobile versions of Terraria.

The Flying Knife being controlled. Note how it whizzes around the cursor instead of following it perfectly.

The Flying Knife is a Hardmode boomerang that has a 1/4 (25%) chance of being dropped by Hallowed Mimics. When used, it fires a controllable knife. Holding the ⚒ Use / Attack button directs the projectile's general path, although it also continuously moves on its own and ricochets off blocks. When the ⚒ Use / Attack button is released or after one minute of continuous use, the knife returns to the player.

Its best modifier is Godly or Demonic. Both modifiers increase the average damage output by the same amount. However, Ruthless might be preferred if the player already has very high critical strike chance. However, the bonus knockback granted by the Godly modifier is not always beneficial and makes it tricky to damage the same targets. For example, the knife will not necessarily be knocking enemies away from the player. Alternatively, modifiers that reduce knockback (the best being Ruthless) can be beneficial, reducing the distance enemies are knocked away from the cursor.

Notes

The Flying Knife has a tendency to fly through walls at times, usually when in small spaces.
It is possible to swap loadouts while continuing to control the Flying Knife.

Tips

The long returning arc can be ignored if the player leaves the cursor between the knife and a wall. The knife will try to follow the cursor and keep bouncing off the wall, granting a much higher DPS than it would in open space. This is extremely useful against The Destroyer.
The Flying Knife can be useful for damaging both of The Twins at once, though this can cause both of them to go into their second phases at the same time.
If the player is Stoned by Medusa and already has the Flying Knife thrown-out, it can still be controlled.
It can still be used while sleeping in a bed.