[Galadriel55]

After some thinking... Aragorn's trip through the Paths of the Dead.

To first of you, I'm just a tale,
told by the skies, as they unveil - Frodo sees Aragorn's pirate ship in the Mirror
mysteries hidden long ago. - the future was hidden by Iluvatar

To second one, who's bigger still
than me, - Denethor is still the ruler of Gondor. Or perhaps Eomer, who is already King of the Mark
I'm first a fear until - duh, they think he's a corsair.
I show him I can bring your friends; - a whole army of friends!
his trust shall be of importance. - huh? I mean, it could mean a whole lot of things, but I think this is something more specific than that Aragorn was friends with Eomer. Possibly that Eomer trusted Aragorn and gave him, Gimli, and Legolas horses to go look for the hobbits? No. Because "shall" is not "was".

And to the third, whom you don't know,
I enlighten the terror's night, - now that's where it just crumbles to pieces.
and in mine and the Other's flight - that Other (may he be stabbed with dragonglass!) just kills it again. Aragorn leaves Theoden's side as if to escape battle and he travels at an impossible speed, either of which could be called flight, but he does it with over 30 men, not with one other! On the other hand, Aragorn is called Wingfoot by Eomer, but that is a totally different storyline and he still has more than one companion.
I save more than the tale did show. - well, he does, in the end.

Still no answer.