i tried to make sense of the verses but failed..
the most obvious meaning of the chorus for me, is that some girl made his life better/made him a better person (spit-shining his halo--> using her own self or "spit" and "shining" him or making him better) but then maybe left him or lost interest, thus the "And left it to decay". But it seems that there must be more to it than that, when you look at the verses.
i tried to make sense of the verses but failed.. the most obvious meaning of the chorus for me, is that some girl made his life better/made him a better person (spit-shining his halo--> using her own self or "spit" and "shining" him or making him better) but then maybe left him or lost interest, thus the "And left it to decay". But it seems that there must be more to it than that, when you look at the verses.