Hey bro, I believe that I confused you by my response. It was made out of my own incredulity, and didn't really have a target, except for the "Sealing Spike being the Master Sword" issue. Sorry for surprising you like that. xD
He didn't really turn into it in a specific way, most of the time. He just turns into that form to fight you in most of the games. A Link to the Past implies he took that form either as a result of the corrupting influence of the Dark World, or because it was part of his wish to gain power, but this explanation is largely irrelevant to the rest of the games.