There are currently two defined ways to unlock this exclusive axe. It is not supposed to be easy. It is not supposed to be something lots of people attain. http://fortresscraft.wikia.com/wiki/Neoteric_Axe
IF you think you are one of those few people, then here are the CURRENT ways in which you can earn it :
1) Get a FC-positive Youtube video with over a million views
2) Create a pic that is good enough for the front page. See the link for details. Post your image in this forum (inline, PLEASE!)
The reason I'm doing it like this is simple; I just got over 50 tweets and emails and skype messages with "Is this good enough?"
A few 'is it good enough' notes:
IF at all possible, the pic should be "Not possible in Minecraft". You guys are way better at pushing this engine to it's limits, to do things that truly aren't possible in other engines; plenty of customs, plenty of reflective water and things at an angle.
If you have a great world, and no way to take a pic, there are plenty of people who will help you!