I think Germaine Greer may well have been right when she said that cunt was the last verbal taboo. I suspect it may have been the first sexual taboo as well, as an early dictionary defined it as something along the lines of "a nasty word for a nasty thing".
Swear words are surely mostly derived from blasphemy and have a religious context. Someone above mentioned blimey. An American schoolfriend, when asked to put a Shakespearean speech into modern English, puzzled for a while over "Zounds". She tried to think of a commonly accepted modern blasphemous expression and, being American, eventually settled on Jesus H. Christ. I don't think she got an A.
For really weird swearing within a religious context, look up Québecois French usage (tabarnak).
Sexual "swearing" is a different kind of offensive, similar to other deeply unpleasant usages, such as nigger. Incidentally, the latter is still generally regarded as more offensive than cunt, even though some black people have gone further down the "reclaim" route than the Vagina Monologues with cunt.