Nail

Nail is the term used to describe the bladed weapons wielded by several enemies, NPCs, and bosses in Hollow Knight, including the Knight.

The Nailsmith in the City of Tears can upgrade the Knight's Nail up to 4 times if given enough Geo and Pale Ore, which increase the damage of Nail strikes.

The Fragile Strength/ Unbreakable Strength and Fury of the Fallen Charms also increase Nail damage.

Upgrades

Nail-bouncing By jumping and slashing down with the Nail on environmental objects, spikes, or enemies, the Knight can bounce. This move, known as "Nail-bouncing", "pogo-jumping", or simply "pogo-ing" is useful for fighting enemies and platforming. A number of areas can also be accessed early through Nail-bouncing.

In the Fungal Wastes, there are purple mushrooms which the Knight can Nail-bounce on to bounce higher than usual. They must be used as a platform to access the Mantis Village and other locations before obtaining the Mantis Claw, Monarch Wings, or Isma's Tear.

Aside from these mushrooms, there are a few other times where Nail-bouncing is required:
 * To obtain a Vessel Fragment in Deepnest by Nail-bouncing on Garpedes.
 * To obtain a Hallownest Seal above the Stag Station in King's Station.
 * To complete some parts of the White Palace and the Path of Pain.

Trivia
 * Upgrading the Nail does not change its appearance in the Knight's sprites.
 * Some enemies wield greatnails and nail-lances; however, the Knight can wield neither.

Гвоздь Aiguillon 骨钉 Ostrze Aguijón Nagel Aculeo Ferrão