Tarot decks were created in about the 14th century for games and divination. It is believed Napoleon played solitaire with Tarot cards on Elba. As Tarot cards branched off to the standard playing cards, playing cards and more specialist Tarot decks were all used for divination: casting fortunes.
Prior to Rider-Waite, there was considerable variation between Tarot decks. Almost all were custom, one off works of art. Since Rider-Waite, it has become a standard template, although it need not be.
For Malifaux, using the fate deck as a divination tool as well as a game aid has a certain attraction. Divination spreads could be used to create story lines for fiction, campaigns or scenarios. It could also be used to generate characters and or character personalities for a role play game.
A couple of issues:
Use the existing 54 cards or create a major arcana (trumps?) {Technically, the existing Jokers are Major Arcana}
If a major arcana is created, how many cards will it have? Rider-Waite has 56 minor arcana and 22 major arcana, 78 cards.
My personal preference would be to use the existing 54 cards only; adding 15 or 20 major arcana cards, say, the masters and henchmen of the 5 factions, might be more fun. I would print cards with pictures on one side, text on the other, and use them in card protectors, using the backs for "notes."
What say you?