An Hero of Time
I believe it is rather SS's Link or just a perception of Twilight Princess' Link's inner hero, rather than an actual past hero.
Link is taught mysteries from the ghost of the hero of time. Since he returned to his childhood, he'd felt regret that he would leave his name as hero. Therefore, the "son" of Link speaks proof of the courage he inheirited mysteriously.
hero of time.
Unless if multiple translators are wrong, then he's the Hero of Time.
How he got the armor and learned the sword skills? I guess we'll just have wait for that in a future installment that ends the hero of time's journey... If they ever do make one, that is...