Thread:An Advocate for Manga/@comment-27078917-20151015215614/@comment-27082825-20151015234734

It is hardened (crystalized), however, other hardened Ukaku haven't been shown to be as destructive on average, but it could amount to skill as you suggest as opposed to genetics. I just suggested that possibility, based on other similar situations like Minami's Bi-like Koukaku, or Kuzen's Kou-like Ukaku, or even Grave Robber's Rin-like Bikaku.

I'd say a Kakuja would improve ones basic pysical capabilities. I'd say about a 0.5-1 difference in Str, Sp, and probably Stam as a general boost, and depending on their RC type, certain stats would continue to increase. Like when Arata became a Kakuja, I'm sure his strength increased considerably seeing as he had to adjust to lugging around his armor.