In reply to:

Irony is the soft end of sarcasm.

Yes, as long as the discussion is strictly about verbal irony or perhaps conversational irony and not about, for instance, dramatic irony. I think we discussed in previous discussions the dramatic irony of Oedipus' speeches in which he promised to ferret out and kill the king's murderer--all the while the audience knowing full well that it was Oedipus himself who had murdered the king. Excellent example of dramatic irony. No soft end of sarcasm applicable in this case.

One of the problems we have here on this board whenever discussing an aspect of irony is the subject is so dense and broad. There are literally volumes written on the subject--entire books about the subject of irony--and apparently the subject never dies down and goes away since new volumes continue to appear in academic libraries.

But having said that little bit of not much above, I still like very much your phrase: "Irony is the soft end of sarcasm..."