[LadyBrooke]

I'm just guessing but is it Aragorn?

Born within a hidden fastness, - I'm not sure if he was born there but he was raised in Rivendell.

I've travelled far and wide, - he traveled all over Middle Earth

Providing hope against the darkness, - Estel means hope and his mother said she gave hope to M-E but kept none for herself

Enemies on every side. - not sure what this would mean

Many a master have I served, - He served Etchelion and Thengel at least just off the top of my head.

The greater and the lesser too, - Rohan was considered lesser than Gondor by many according to Faramir's words in Ithilen

Given a new name, well deserved, - how many names does he have? Too many at least.

(Trust in me and we'll win through.

Threatening, when it was right,
Or cutting through the enemy,
I'll not for the unrighteous fight,
For that's my point you see) - not sure about any that.

I'm probably wrong about it though.