Right. That's exactly what the Catechism says. No need for qualifiers or spin from you. It says what it says.
It's a grave mistake to dismiss those parts of the Catechism with which you disagree as "weasel-words". Parsing and equivocating with regard to this document is sheer foolishness.
Saddam will be executed of course, don't worry.
And it will make zero difference to the current carnage in Iraq.
They ARE weasel-words. Nothing foolish about it. Modern society does NOT have an effective method of preventing sociopaths from doing harm again. They "could" have, but they don't. There are at least two possibilities--permanent incarceration in solitary confinement, or surgically severing the spine so the sociopath has no use of arms or legs. In both cases, the individual can still repent and save his soul.
"Rarely" is not "never".
Also bear in mind that two teenage highwaymen were hanged (for mere armed robbery of a coach and no more) from the rafters until dead at the coronation banquet of Pope Sixtus V, one of the most remarkable (in a positive sense) of all the popes, that Catholic doctrine is not a trend of the week matter and that we may be allowed to make history but that we are not allowed to REmake history. What is right and what is wrong is not dictated by the calendar.
It just may be that John Paul the Great of happy memory had seen more than enough slaughter in his lifetime in mid-century Central and Eastern Europe and was nudging policy. We can always count on the ever anti-American Cardinal Martino to chime in against the interests of the USA and of Western Civilization. This story is being spun by him and b those elements of the press/media who are attributing Martino's words as though they were Benedict XVI's words.
The purposes of executing Saddam Hussein include justice, retribution, prevention of further crimes by Saddam and discouragement of would-be Saddams.