I saw a program that compared the katana with the european longsword. The program was hosted by R. Lee Ermey who is best known for his role as Sergeant Hartman in Full Metal Jacket. Various tests were done where the swords were used against ice blocks, straw torsos, and plate metal armor. In all the tests the katana performed better. So, the katana must be an all around more effective sword, at least that's what the tests showed.