The Pirate Boarding Axe is available for people who preordered the Assassin's Creed III on Amazon
It is only available after you have finished sequence 6
Even with one eye, ye could easily recognize easily the fine craft of this pirate's axe. The shagreen strops covering the handle give it a better handling during intense battles.
How to access Pirate Boarding Axe
Complete Sequence 6 of the game.
Once completed, Go to Homestead Manor
Your Pirate Boarding Axe will be located inside.