I think I figured it out.
Born in the East, - Made in Gondor
I have seen many lands. - During the journey
Silver-clad, - it was tipped with silver
I announce great beginnings. - It was first blown at the beginning of the journey
Announcer of trouble, - It was blown for the second time at Parth Galen
Herald of death. - and third time just before his death
I did as was foretold - if it be blown at need anywhere within the bounds of Gondor, as the realm was of old, its voice will not pass unheeded."
But to bring only pain. - Its remains were found by Denethor and Faramir and naturally seeing them was painful