I wrote a short story here http://zecountess.deviantart.com/art/Mirrors-440990952
whose ending explains everything that is narrated before. The feedback I got from my readers is varied, and none of them are anywhere close to what I had in mind.
To paraphrase Umberto Eco, there is the book that the writer writes and the book that the reader reads.
As of now, I call it Mirrors. Would it be fair to change it to 'Psychomanteum' to nudge readers a little?
I think that we should take the readers' expectations into account when writing a short story. Giving your story an exotic title makes me expect something overly sophisticated (I know, I tend to fold quickly. Just puff out your literary chest a little, and I'll walk out of the bar rather than draw my six-shooter).
I think your story's title should be changed if you're confident that it'll draw your readers' attention. Just make sure that you get the audience you are aiming for. If your audience are the kind of people who find googling something a chore (believe me, some people choose to back away from a story with an unfamiliar word rather than look up a good dictionary), you might want to reconsider changing your title.
I think you should heed Eco and let your story go. Stories are like children: they don't live their lives for you. If you force them to make you happy, you destroy their spirit.
If this were my story, I would chose "I could hear someone sobbing softly" as its title.
The title should attract the reader. It is like the cover of a magazine, a movie poster, or a newspaper headline. It should not explain, but grab attention. The explaining must be done within the tale.
If the readers of your genre find "mirrors" or a "psychomanteum" gripping, then those are good titles. I personally find "mirrors" boring, because they are such a worn-out subject, and "psychowhatsthat" off-putting, because I must make an effort (of looking that word up) before I can even begin to read, and it makes me expect something either learned and difficult and unentertaining or something badly written and filled with clever name-dropping to impress.
Look at popular books or stories and see what kind of titles they have. Usually they are condensed versions of first sentences and, like them, chosen to hook the readers.
I've witnessed many writers and musicians being coy about what a song, story, or poem means because they don't want to dismiss any special meaning that the reader or listener might have attributed to the piece.
If your novel becomes a classic, then scholars and Cliffs notes will make your point for you. I say, why not be clear instead of coy? If you're talented, you can lead most of your audience wherever you want them to go. If it's important to you that the reader gets it, then take the time to help them get there.
Readers don't seem to mind the obvious, as long as it's entertaining.
If you can change your title to something that helps the reader reach the conclusions that you want them to reach, without being too much of a spoiler, then do it. Yet, it's questionable whether "Psychomanteum" is more clear than "Mirrors".
Go with your heart's desire.
Every story that a writer writes, the reader reads differently. It is because each one of us has different perception and interpretation of stories. I doubt that two person could even interpret a piece in exact same way, down to the feelings and nuisances of emotions we feel whenever we read a piece, much more to match it with what the author has in mind.
I suggest that you just write, not for your readers but for yourself. Then let them think, interpret, and relate to it the way they want to. The title may have bearings but it is not the be all and end all of your piece. Remember, the story will always speak for itself.
There's a fine balance between writing for the writer and writing for the reader. On one hand, you shouldn't condescend to readers, and not everybody is part of your audience, and so not everybody needs to "get" the story; on the other, you do generally want your intent to come through. The balance is different for every story.
So that's a non-answer. But in this specific case, I don't think the title needs to nudge anyone anywhere. I think you're just fine. I actually like "Mirrors" much better than "Psychomanteum"; the second just means nothing to me. Obscure words aren't bad, and again, you shouldn't condescend to people like me, but I'd bet that a large percentage of your readership would find that it is not meaningful to them at first glance.
