While the neutral B may look different, it has the same function: Hold for power, release for sword attack. (gonintendo.com)
It's fun at first to be able to lift your left arm and see your shield come up in front of you, or swing your right for a heavy sword attack. (techradar.com)
I think mainly because they were really pushing the motion controls, even going as far as having enemies block certain sword attacks. (gamercrash.com)