User blog comment:Jopjopjop/Volume 18 Spoilers/@comment-3965848-20150515062944/@comment-26322543-20150515220355

Yes, I think Penetrate only works on "special" defences too. (aka anything that's not a "part" of the target) And yes, the lack of information makes it possible those techniques are more complex than we know, but I only wish they would get more abilities. Just my personal preference. :P