A Hero Becomes Legend

The title of this video clip is "A Hero Becomes Legend", which phrase is also shown in the clip itself.

I think if "legend" here meant "person" that it should be countable and have "a" like "A Hero Becomes A Legend".

But since it doesn't have "a", I think that "legend" here means a "story" as in "Legend has it that...".

Am I right about the meaning of this word?

Also, is it possible to use the word as a countable noun meaning "a person" in this title and in the clip and say "A Hero Becomes A Legend"?