Does Tales Of Vesperia Have Multiple Endings? *POSSIBLE SPOILERS*

Just wondering because I beat the game last night and I had beaten "Symphonia: Dawn" on the Wii prior and it had 2 endings. Also, I heard about a secret chapter involving Estelle if you use a certain item during her boss battle at the Alexei "arc" (or was that secret mission?). Have I uncovered everything the main plot has to offer with just one playthrough? Excluding sidequests.

There's no second ending, there's only a secret end boss. As for the Estelle thing, its only a secret mission. Earlier in the game if you slept in the desert town inn (i cannot remember the name) a cutscene could be triggered, with estellise discussing with Yuri about something and at the end of said cutscene she'd give you a memento of her mother.

This memento can then be used during the fight against her before battling alexei, thus giving you the 5g for the secret mission.

As for the secret final boss its all sidequest related, you need the 7 fell arms and when you battle dukes 2nd form. Once you beat it he's going to have a 3rd form powered by the fell arms, though it does not change the ending it only add extra dialogue between the end of form 2 and the beginning of form 3.