Well yeah, 'corrupted' was the wrong word to use--I just woke up and haven't had my caffeine fix yet. But it certainly explains why Marth went from awesome to nearly-crazy, although there are other factors aside from Falchion being a holy weapon, but it certainly didn't help. Hell, it could have altered Anri, which we don't know because IS didn't give us anything except that Anri was awesome--because the game follows Marth, so he is biased.