Psycho Knife

The Psycho Knife is a Hardmode, post-Plantera melee weapon that has a /  chance to be dropped by the Psycho during the Solar Eclipse event. When holding the Psycho Knife and standing still, the player will quickly enter stealth mode, causing them to turn almost completely transparent, move much more slowly, and no longer be targeted by enemies.

Stealth mode is engaged gradually over the course of about one second, during which the weapon's stats are steadily boosted up to the following values:
 * Damage +300%: 340 (from 85)
 * Critical chance +30: 34% (from 4%)
 * Knockback +100%: 7 "Strong" (from 3.5 "Weak")

Stealth mode is disengaged when successfully attacking an enemy, when switching to a different weapon or when riding a mount. Swinging the weapon alone does not cancel stealth, nor does walking or flying. Standing still again afterward re-engages it. Moving or swinging the weapon during the one-second transition period, however, will cancel stealth mode.

Due to rounding, the Light modifier gives the same speed bonus as Legendary, with fewer other bonuses.

Tips

 * Melee weapon projectile stats from any weapon will be boosted during stealth, which can be useful for dispatching large groups of enemies while maintaining a distance.
 * As an example, using a melee weapon that shoots projectiles, such as the Terra Blade or the Meowmere, and switching to Psycho Knife before the projectile hits will result in extreme damage to enemies hit if stealth builds up before the projectile strikes. The Meowmere uses this to especially great effect due to its projectiles being able to hit many times before dissipating.
 * By gaining the Striking Moment buff from the Brand of the Inferno before switching to the Psycho Knife, one can easily deal over 2,000 damage in a single hit if it is a critical hit.
 * This damage can be drastically increased to well over 7,000 in a single hit when utilizing banners in Expert Mode alongside damage boosting gear such as armor and accessories, marking it one of the highest damaging setups in the game.
 * A hook or any dash accessory (Shield of Cthulhu, Master Ninja Gear or Tabi) can be used to great effect to move faster while in stealth mode. Simply hook the floor while in stealth mode and jump; it will boost your movement speed significantly.

History
Couteau de Taré 사이코 칼 变态人的刀