What is this fantasy style card game?
This absolutely sounds like Munchkin or one of the many versions of it by Steve Jackson, and if so it definitely IS a popular game. Equipment cards, monsters, curses and some form of class cards are common to all the versions, many equipment have special restrictions or buffs on top of the basic number bonus, and you use them (and potentially help from other players) to fight monsters with the goal of getting to level 10 first.