In my mind It is indeed about the Arthurian legend.
The singer is Lancelot, "there's no patron saint for silent restraint" - he can't act because of his love and respect for Arthur.
The love he is singing about is Guinevere meaning 'white spirit' deriving the term "the spirit has left you baby" meaning she's not herself, she's also Arthurs' wife.
When she finds she fancies Lancelot, she decides to have an affair, though upon reflection and confrontation she "ups and leaves" making her decision to become a nun, Lancelot doesn't understand: "it's a question of needs and not rosemary beads, in the end".
She always has loved the "black knight" Arthur though, he was always her true love, she needs him, she goes back to him.
Lancelot the singer is the white knight, he is devastated, he thought she loved him, now he's "empty as a drum". He was prepared to give up his honour, his friendship to be with her, though he takes this risk, and it all goes sour on him.
He's lost it all, he cannot do anything, the sword is not in the lake - meaning Arthur still has it, he is still alive, and whilst he is alive, she will love the black knight over the white knight, always.
In my mind It is indeed about the Arthurian legend. The singer is Lancelot, "there's no patron saint for silent restraint" - he can't act because of his love and respect for Arthur. The love he is singing about is Guinevere meaning 'white spirit' deriving the term "the spirit has left you baby" meaning she's not herself, she's also Arthurs' wife. When she finds she fancies Lancelot, she decides to have an affair, though upon reflection and confrontation she "ups and leaves" making her decision to become a nun, Lancelot doesn't understand: "it's a question of needs and not rosemary beads, in the end". She always has loved the "black knight" Arthur though, he was always her true love, she needs him, she goes back to him. Lancelot the singer is the white knight, he is devastated, he thought she loved him, now he's "empty as a drum". He was prepared to give up his honour, his friendship to be with her, though he takes this risk, and it all goes sour on him. He's lost it all, he cannot do anything, the sword is not in the lake - meaning Arthur still has it, he is still alive, and whilst he is alive, she will love the black knight over the white knight, always.