A character is invisible, hidden from watchful eyes and cannot be targeted by foes. The effect is temporary.Final Fantasy XII description
Vanish and Banish have the same name in Japanese.
Turns the target invisible.Description
Vanish is an Effect spell learned from Phantom. It grants the Vanish status to the target, making all physical attacks miss. Celes learns the spell naturally at level 48. The spell is vulnerable to Runic.
The Invisible status is famously glitchy, making targets vulnerable to magic they are not supposed to be; such as allowing the player to defeat any enemy with Death (this has been fixed in the Advance release) and making it possible to cast Raise on living characters to restore HP. Vanish can be cast by Gobbledygook and Level 40 Magic.
Makes a party member disappear.Description
Vanish is a Blue Magic spell learned by eating a Drakan, Vice, Hornet, Gnoll, or Troll and costs 8 MP to cast. It can't be reflected and works with Return Magic. Vanish causes a targeted character to be immune to physical damage. The effect is temporary, and it ends prematurely if the target has magic cast on it. Vanish can be cast by Drakan, Gnoll, Goblin Mage, and Iron Man.
In the original version, Vanish is a Arcane Magick spell that grants Invisible status to the target for the (initial) cost of 24 MP. Vanish requires the Arcane Magick 4 license that can be purchased for 50 LP. The spell can be bought in Nalbina, Mt Bur-Omisace, and Phon Coast for 4,900 gil.
In the Zodiac versions, Vanish is a Time Magick found in the Time Magick 3 license for 40 LP. Only the Red Battlemage and Time Battlemage can acquire the license, while the Famfrit can allow the Machinist to learn its area-of-effect version, Vanishga.
In the manga version of Final Fantasy XII, Balthier challenges Vaan to a game where he catches a coin and Vaan must guess which hand it is in. Vaan loses and Balthier explains he won the coin flip using the magic spells Decoy and Vanish to distract Vaan, toss a fake coin while throwing the invisible real coin to Fran, and Vaan lost because he was too naive and didn't watch his surroundings.
While not a crafted ability, Banish is a magicite ability that can only be used by players when they summon the Phantom esper. The ability grants a single ally an elemental barrier that enables them to avoid a single holy-elemental attack. Vanish has a default trigger rate of 20%, with 50% trigger rate at max rank.
Despite the ability name, Phantom's Banish is in fact the recurring Vanish spell with a mistranslated name. This is likely due to the Banish and Vanish spells sharing the same spelling in katakana characters in Japanese.