I am the king beyond the wall.
I am three chiefs. To many, a symbol of hope and peace.
And yet, I could adorn the banner of a coward.
What am I?
The king and the chiefs are not literal. In fact, the first line could just as easily read, "In winter I am a conqueror". I am just a nerdy-geek and couldn't resist adding a little nerdy-geek cultural reference.
"the banner of a coward" is almost literal, albeit stretching the meaning of the word "banner".