Be carefull about trying to get something past security. Sometimes it's easy, sometimes it's not. Depends on the quality of the security screeners. But keep this in mind. If the GSC (ground security coordinator), the person (final decision maker) who is nearby when you are going through the screening process, decides he or she doesn't like your tool, you may have no other option than to leave it behind. It is not really possible to have it put into you luggage once your bags are checked. And once left behind, there is no guarentee you will ever get it back! If you have time, you may be able to mail it, or if your lucky, you can make arrangements with the airline to mail it to you, but I've seen the "lost and found" box at the airport where I work. As far as checking it in you luggage, you can check a gun in your luggage successfully if you claim it. I don't see a reason you would have to claim a knive though.
Note: I do not work for an airline, but have been certified as a GSC once for the private company I work for - we handle private airline charters. If the screener belives you may be a risk, he or she can take toothpicks and ball point pens away from you. I've seen screeners let hand grenades through (when suprised tested by the FAA). A friend of mine was extremely good as screening and full of common sense. He was rare.
Just my .02's on this subject.
lear.