I was wandering on one czech unofficial morrowind fan site and in "Weapons" section i found some axe called "Wings of the Queen of Bats". There was written, that this weapon couldn't be apparently found in game. Author found it only in TESCS. Maybe i should trust her, but the same text was written about the Eltonbrand. And later i learnt, that it is in game.
Here is the ultimate question: Is this axe in game or is it not? I believe someone here knows it. Thanks for your interest.
Picture from that site:

It is not in the game. You can add it via the console. When people tell you something is not in the game it can be that they are looking at the construction set and find the number 'in game' is 0. However that is misleading because anything that is only available as a reward is shown as 0 and IIRC (marxist will no doubt correct me if I am wrong) certain random items are also shown as 0. Something like Mephala's teacher for instance can sometimes be found in random temple loot when you reach a high enough level but is not actually in the game in a specific place. A complete, and I hope, correct list of unique weapons is pinned in spoilers and includes the wings of the queen of bats.

AFAIK in addition to the axe you mention the following are NEVER in the game (from tcs), please correct me if I am wrong:-
Anora's club
Azura's star (as a weapon)
Dart of Judgement (iron version)
Herder's Crook
Mark's Mace of Pooftah Love (cannot be added via the console either)
Mehrune's dagger (ebony item)
Nordic Silver longsword (tracker)
Riekling Minion Lance
Spirit-eater
Staff of Llevule
There are also 'false' and 'fake' Sunders with different references that I do not believe to be in game.

No doubt I have made an error somewhere. Please point it out.

Where is that thing hiding? Couldn't find it in the editor...

Lordy, lordy, this is an antique thread.

AFAIK the mace in question was removed in the GOTY version. I suspect it shouldn't have been there in the first place. One of the developers having a little joke maybe.