The Brits confiscated the altered corkscrew (sans blade) from my carry-on. Apparently, they have a problem with anything 'pointy'.

Rather than alter another corkscrew, I was able to find another that should meet the TSA's requirements. It does not have a blade, just 2 small metal nubs to cut the foil. Actually, it looks like what Mark was talking about. The only downside is that at 0.35lb, it's a bit heavy.