Hi, I am Arju.Today I am going to tell you how to get Altair's armor and sword.
Before we do so, turn in your one codex to Leonardo. 
With all six seals,Go in the villa, enter the room on the right (architect room), use 
the passage in the back of the room to get to the codex room (back right of the mansion),
go straight, through where there used to be a bookshelf, to a long corridor that leads 
below the mansion, into a large room with 6 statues and the armor behind a grate in the
middle.
Go up to each of the statues and press Lshift (assuming you have all the seals).
Once you place the 6th, it should open the grate in the middle, giving you access to 
Altair's armor whitch has no damage.
When you get Altair's armor, go to any blacksmith's shop in villa.And there from the 
sword menu you can now buy Altair's sword. 
If you face any difficulty to understand it then plz email me. Thanks everyone.