High Summoner Galatea:
In the old days Summoners created their own cards, but the cards have become so sophisticated that they must be created by a special craftsmen. Note that you are not yet an official Summoner and may only receive Apprentice Arcana Cards. Perhaps the day will come when you may possess a Major Arcana Card, a card that is only held by the top Summoners of the land!
The card you will be making now is for use in the trial, so it need not be ostentatious. You must seek out a craftsman who knows the methods for creating arcana cards. Trader Lara in the Town of Dion will probably make a card for you.
She works rather slowly, so I suggest that you order a good supply of them up front.