Never any explanations. That's just on us fans! The showrunners never intended it to be magic and weren't interested in slowing down the episodes with figuring out where the swords were for everyone's wardrobe, except when it made the story better. Like the times Duncan goes jogging and leaves his katana just out of sight in his car, and has to run frantically to get it. I suppose that could make them magicians in the sleight-of-hand sense.