Note: You have to write the class in lowercase letters, otherwise you will not get the feat. (ie "warmage". not "Warmage")
They can be obtained by winning a certain amount of blackjack hands in a row (12?), depending on the bet, and are also very rarely found in dungeons.
The sprite number for the business card is located at 383 (Row 11, Column 20) by the character sprite numbering system.