for the real answers, I suggest the following;
realultimatepower.com
or askaninja.com
or any book by ashida kim.
Seriously Matsumi is about the only guy on earth with any plausible claim to being a ninjitsu practitioner...and alot of people are skeptical about that. Having balance like that can easily be accomplished by practicing on those damn things daily. The heavy "deathblow" thing was bullshit. Anyone can deliver a hammer type strike to the solar plexus. Anyone.