Falter is an anagram of Raftel and it's quite funny how the word means to stop being strong or successful or to begin to fail or weaken.

It is hinted by the folks of One Piece and as most of us assumed that One Piece is at Raftel. So if the treasure One Piece=Rio Poneglyph, a very fitting place indeed, the place where they'll know the true history, the void century and the downfall of the Ancient strong/powerful Kingdom.
Now if One Piece=Weapon, it still fit the description, as Whitebeard said that when someone finds that treasure the world will be shaken to its core. It could be strong enough to stop/weaken the WG or whoever the enemy is.

Now my question is who and why hide or place that thing at the end of grand line? Okay so for the who part obviously we know that Gol D. Roger is the one who lead it there but why?
So that someone can find and take it back to the other half or to destroy the Red Line that is blocking their way? Man those voices heard by Gol D. Roger must been really bored

I do like the idea of a united sea but uniting means to bring together so as to form a whole and that would mean destroying all land mass that separates them but if One Piece will only be use or for making a passageway on the Red Line so much for wealth, fame and power I'd feel duped if I were Luffy.

This also remind me of the statement made by Luffy at skypiea arc after seeing the vearth statue "you guys yearn that long? is there something wrong with you?" for a passageway<– referring at the will(Roger's) that has been passed down from long ago as stated by Whitebeard.