User blog comment:Godisme/Shades of the Bond/@comment-44061-20111130194255/@comment-3430885-20111201011147

I Believe the reason Ichigo's Shikai and Bankai changed so much is because more then one person put their power into the sword that gave Ichigo his powers, Wherein when he first got his powers it was Rukia's power that granted him his previous Shikai and Banki, While now it was all of the Captains and Lieutenants of the Gotei 13 who poured their powers together in the sword