Phantom Equip

Phantom Swap is the unique skill given to Hunter Kasai during his time in Sword Art Online. This skill allowed for one to swap between any weapon quickly, regardless of where the weapon is stored. Hunter was given this skill due to his reaction time being high enough for Dual Blades, but was beaten by Kirito as the Dual Blades owner. Instead, the Phantom Swap skill was awarded to Hunter not only for his reaction times, but for his ability to adapt quickly as well.

Description
Phantom Swap is a Unique Skill that requires the user to have a high reaction time, as well as high flexibility in combat, changing their attacks strategically to inflict damage in many different ways. The skill itself allows the user to swap between any weapons the user has, equipped or otherwise, instantaneously. By utilizing this skill, Hunter, the owner of the skill, can swap between using his katana and curved blade skills, to a scythe or two-handed battle-axe. Using his scythe, Hunter can spin it around and uses its enhanced speed and agility to essentially move around and glide around the battlefield with incredible agility, nowhere near other Unique Skills that focus on speed and maneuvering, but still quick enough that his Acrobatics skill allows him to free-run and jump around the place, letting him pull off aerial combos as well. With the Battle-Axe, Hunter gains access to hard-hitting, heavy attacks that deal as much damage as possible, but limits its aerial combo capabilities; even Hunter's high Acrobatics skills only allow Hunter to jump extremely high with the axe equipped. In order to allow for instantaneous switching between weapons, Phantom Swap has no cool-down period.

But this skill does have its limitations. Hunter can only swap between three weapons, and none of them can be the same weapon. Meaning, Hunter can't switch between a one-handed long-sword to a two-handed long-sword, or a one-handed battle-axe to his two-handed battle-axe. Its use is limited to fighting only, so he can't use it in safe-zones, unless he's in a duel. Also, Phantom Swap can be negated by a Dual Blades user because of Phantom Swap not allowing for Dual Wielding. Hunter's speed is also outmatched by skills such as Zero Shift, or the Blur and Shadow Travel REALITIES. The Phantom Swap's weapon switching speed, however, is unparalleled, so there is that.

Trivia

 * The Phantom Swap was inspired by DmC's Dante's ability to swap between weapons on the fly, and it does come in handy.
 * I chose the name "Phantom Swap" because it sounds cool. Also because it's an excellent representation of what the skill can do.