Thats actually pretty funny that you would ask because I in fact do have a magic trick that uses a sword. Here´s the effect: I have a sword that hangs on my wall that has a pierced playing card on it, I then ask whoever to guess what the playing card is and it turns out to be the exact playing card they named.
Basically what is happening is that as they are naming a card I [edited to remove method] using a method from Daniel Madison's Advocate. You could also dress this effect up by telling a story about how the King of Hearts has a sword through his head or something like that. This is just an idea, so obviously you dont have to use it, but if you do, let me know! I´d love to hear how it went.
If you don´t know what the advocate is, its basically [edited to remove exposure].
Even if you don´t want to use it for this effect, it still should be something every magician should eventually get, so i´d highly recommend it.