The other day I needed to get a new trench coat. I've had my old one for over ten years, and its well worn, well loved, and even has a hole or two in it. In short its time to retire it. So the other day I went to Burlington coat factory and found a very nice replacement. As soon as I put it on, I felt like I was settling into this warm, comfortable garment that served to not only protect my body from the cold but also, in its own way, became a magical robe of sorts. I've actually felt that way about all of my trench coats.
For me a trench coat is a magical garment. It's a lot like a robe, really. It's got nice long sleeves, and it flows most of the way down your body, plus it wraps around you to cover your entire body. When I'm wearing a trench coat I feel like I'm wrapped not only in the cloth, but also magic itself. Perhaps part of what I like about a trench coat is that it is just a bit formless. When you put it on, you can't tell that much about the person's body or what s/he is concealing underneath the coat. As someone who's grown up with some street smarts, I can tell you that anything which is concealing in that way is quite useful as a posturing tool of sorts.
A trench coat is warm. The lining does an excellent job of keeping your body heat. That warmth reminds me just a bit of the description of Raistlin and his body heat. When I put the coat on, and I feel the heat as a result, I also feel like the magic is surrounding me. I've done enough rituals out in the winter cold to appreciate a good trench coat and how marvelous it can be for keeping me warm, but also how it feels as I move around and the garment presses against me, or flows around me, much like a magician's robe might.
I don't know that there is any inherent magic to a trench coat or any other garment, but I think what it evokes for me is what makes the coat special. It's how I feel as a result of wearing it that really matters. That experience is magical and in turn it makes the coat magical.