Here's my guess:
I am who I am, Returned to the world,
Rand al'Thor is the reincarnated Lews Therin, from the Wheel of Time series.
To Save or to Damn,
My banner's unfurled.
Rand is ultimately responsible for the outcome of the Last Battle, win or lose. He fights under the Dragon banner for a large portion of the series.
So many names I have,
But one always true.
Rand is called a lot of things, "The Dragon Reborn", "Lews Therin", "Car'a'Carn", but his name is Rand al'Thor.
No golden Calve,
But worship you do.
Play on words. His golden dragon tattoos are on his forearms, not his calves. He's often worshipped by those who believe in the prophecies about him.
My people, they came.
Their weapon they bring.
Few know their true name,
And its familiar ring.
This is the stanza I'm not sure about. It could mean several things. Asha'man bring Saidin as a weapon, but they don't know they were once all called Aes'Sedai. His friends come and fight with him, and on some level know about the whole Wheel reincarnation thing, but few are aware of what their names used to be in past lives.
I did sneak away,
Now the battle is o'er.
After the last battle, he silently left his tent without his army noticing.
Power, all that I say.
Rand gained some sort of unspecified superpower after the last battle. He cannot channel anymore, but can just will things to happen.
Who am I? Fear or adore?
He switched bodies with Ishamael during the last battle, so if anyone recognized him it'd be as a villain. Those bonded to him can sense that he's still Rand.