Shiva, being the Ice aeon, is vulnerable to Fire. Nearly all of her attacks are Ice-elemental. Her ultimate attack, Diamond Dust is non-elemental and cannot be absorbed. Heavenly Strike halves HP and MP and causes Stop.
Using the Garment Grid Ice Queen or accessory with the Ice Eater auto-ability means the character will be healed by Ice attacks. It is useful to augment the party with Haste. Good dresspheres to use are Dark Knight, Black Mage, Alchemist, White Mage, Samurai, Berserker, or Warrior. Even without Ice Eater, the battle is not too difficult if Protect and Shell are applied on the party at the start of the fight. Flametongue and Firaga are good attacks to use against her.
Having Auto-Haste, Ribbon, or Ailment Def. is recommended to block the Stop effect of her Heavenly Strike attack.
Shiva can be added to the Fiend Arena during Chapters 2 - 5 by capturing a Flan Blanco with an S or SP pod, and raising it by 5 levels. Flan Blanco can be captured in the Moonflow, Bevelle, and the Calm Lands from Chapter 2 and Macalania from Chapter 3.
Shiva in the Fiend Arena is exactly identical to her Farplane counterpart.
Shiva (also spelled Śiva) is a Hindu god. The Hindu Shiva once saved the world by consuming poison, giving him blue skin around the area of the neck and throat. Shiva is a male god, but can merge with his consort Parvati to become Ardhanari, an androgynous Hindu god of duality. Shiva is the god of destruction along with Vishnu, who is the god of preservation, and Brahma, the god of creation. Together they are the three principle deities of the Trimurti (Hindu Triad). It is believed he periodically destroys the world, then recreates it.
Shiva has different human forms, males and females. When he was in his avatar form, he spent most of his times in the Himalayan snow mountain. Shiva in the Final Fantasy series is likely inspired by one of his female avatars.
In Japanese pronunciation "Shiba" could refer to English word "shiver", which in Japanese would sound like "shi-ba" or "shi-va".