Blessing is an interesting word, because its roots come from the word for wounding, which is what it still means in French.

Strikes me, though, that anyone who objects to it being used as a sign-off expression would have at least as much as much reason to object to "Goodbye".

Every now and again I sneeze in public, and some passing stranger says "Bless You", the way we do here. I rather like that. I suppose Fionn would find it insulting...