Shikai is secondary form of their zanpakutou(pedang diorang lah)..i've never seen they train soo0 hard to achieve shikai but it would a need lot of training to achieve bankai which is the third and the last form of their sword. to achieve that level, they have to have a deep understanding between the owner of zanpakutou n the zanpakutou itself since they are partner not just a fighting tools that kenpaichi believes in. Ichigo's zanpakutou is always in shikai form (i dunno y) n d name is zangetsu but in bankai form d name changed to tensa zangetsu..which if a shinigami achieve a bankai, their power also increase tremendously..do correct me if im wrong..getsuga tenshou is ichigo's attack's name..

I think I seen this before. Son Goku going Super Saiya-jin for the first time against Freeza. The ultimate bad guy (up to that arc) suddenly found himself helpless against a mysteriously powered up main hero.