(A lot of our English words are similarly derived--thug being the classic example. Our language is infested with metaphor and history: you can't quite get around it. For example, our word for the color reddish-yellow is derived from the Persian word for the orange tree.)
Now, my Rahazeen are not Nizari (not even close, as none of the Abrahamic religions exist in this milieu--in fact, none of our Earth cultures or religions do), and in fact the historical Nizari weren't very much like the As Seen In Folklore version, but they can be treated as somewhat analogous to the As Seen In Folklore ones. And there's not another English word with the right shade of meaning. So I've just spent fifteen minutes fussing with the damned sentence trying to find a better way to express what I mean.
And of course this is ridiculous, because every damned word in the language has similar history, and none of my characters are speaking English anyway, and I am not in fact going to invent six or seven different languages and write a book in them. (Talk about commercial suicide.) And I'll probably wind up using the word, because it's the word I need.
But it bugs me anyway.