It's about a person who used to have everything, people loved him, he was rich and influential, but because of his arrogance the foundations crumbled and he lost it all. In the chorus he makes a plea to someone to 'be mirror, my sword, my shield', to show him his true self, to fight for him and protect him. He knows he wasted his life, that's why he doesn't hope for 'entry to heaven', but concludes by saying that when he 'ruled the world' he was never truthful but now he is, he was humbled and he wants to change. And that's why by the end of the song, which is mostly a confession and asking to be forgiven, for some reason he can't explain saint peter will call his name. This is all symbolic of course it's about loss, it's about asking for forgiveness for past mistakes and hoping for a better future. It certainly isn't about the crusades, the french revolution and monarchy in general.