I wish the images were clearer of the charm. It could be something related to Santeria, as you suggest, it could be a Norse axe, it could be something else entirely. Coming back to this after time away and looking with "fresh" eyes, I feel like we really just know the shape and feel that is unfortunate.
I'm split on the "Copenhagen" being linked to Denmark vs being linked to the tobacco product. A Dane would more likely refer to the city as København, and I think it would be a little weird to have been wearing a touristy t-shirt reading "Copenhagen". Not impossible, just kind of odd when you think about it. A North American who visited recently seems more likely to me, or who had family or friends who brought back a t-shirt from a trip, so maybe someone with a Danish surname or other connection if it isn't linked to tobacco? But I don't think it is a foreigner, JMO.
Money in your sock? I used to do this when younger. I've never been a "purse" gal. I don't think $27 seems like a lot of money for a night out, especially if you maybe needed some for transportation. I could go either way on that. Some of it could have been tip money or something too, if she was working a job with tips involved? Just a thought. Being transient is also a possibility.
I'm not sure about Denise's shoe size or taste in jewelry.