I'll jump in with random comments, which you can take with a grain of salt...
First, I like the red design much better than the blue one. I like the background patterns in both red and blue.
Actually, I really like the red card. The only thing I'm not crazy about is the center medallion looks vaguely native american to my eye, which is out of place with what you're going for, I'm sure. I can't put my finger on it, but it just somehow reminds me of a "dream catcher".
I'll tell you what I don't like about the blue motif...It looks too much like a hodgepodge of incongruous artifacts. The handgun in particular, I really dislike. Also, having 2 items within the gear just looks aesthetically unpleasant. I don't like the radiation symbols either, they are too literal and obvious.
Of all the items on the blue card, I like the gear and the magic symbol best. I'd definitely scrap ye olde pistol, and the radiation symbols.
The red card is a home run, just make the centerpiece less native american looking.
Good luck, this thread is fascinating!