Uncharted 3 – What Does the Ninja Icon Mean?

You climb to the side opposite of Sully. Once there jump to the hanging chandelier and use it to jump to the opposite side of the room. On that wall there is a crank that you can operate using the triangle button that will raise the chandelier and allow you to use it to jump across again.

According to this walkthough:

Observe the statues and the fireplace. This is a puzzle. Lawrence made a note about something like this. Press select to open Nate's Journal. Four knights, with an axe, a shield, a sword, and a morning star. Just like the ones in this room.

You've got to turn each knight so it's facing the right way. Adjust the knights' position to match the the direction they are facing in the journal. The suit of armor thats holding the shield should face the one holding an axe. The knight holding the axe should face the knight with the shield, and the same for the one holding the mace. The knight holding the sword should face the knight holding the axe.