Board Thread:General Discussion/@comment-4906037-20140305155055/@comment-6007020-20140309035646

BoschePG, Shunsui's shikai was based around making children's games into battle conditions, he didn't manipulate shadows. Though that could make for an interesting game ability.

As for the not showing his full power bit, Kubo follows the normal anime logic of "don't show my full power unless my life depends on it".