Adding some element of fantasy in my novel without introducing "magic"?

My story takes place in the late 19th century, mostly urban settings. The MC and his friends are looking for the three artifacts that the evil Illuminati-like organization are also planning on taking. That's the story in a nutshell. My problem with it however, is there I feel there's not a lot of terminology or reasoning behind things in the story to make it seem unique.The artifacts are pretty stand alone and there is no real mythology or terminology behind it that requires explaining past one part in the story, and I feel this is making the story seem shallow and straightforward. Any ideas on how to go about changing this? I'll be glad to add details if needed.