There is no specific spell attached to any of the Arcanum. They're only used to enhance the magic or modify the magic being cast by the mages themselves. Defacing the card or reversing the card itself can affect the spell in various ways, but this only applies to actual tarot cards. As far as the mages know, creating a brand new tarot card is unheard of and in theory should have no real effect.

Having said that, ascribed meanings and other aspects of the Arcana are used throughout Abraxas from fashionable jewelry to fortune telling, which is readily apparent. She might've seen people who have tattoos of their Arcana sign or on an accessory similar to how the zodiac or horoscope symbols are used in modern times. Speaking to the natives will confirm this. Not every use of a sigil or an Arcanum has a magical purpose.