Board Thread:General Discussion/@comment-26511634-20150619122040/@comment-44061-20150619124925

One theory would be that Engetsu can mimic other forms of energy based attacks. Though I dont know that its entirely likely. The most prevailing theory based on what we know from the names of the zanpakuto's and the family connection and what Isshin says its probably more likely that zanpakuto's between parent & child maybe similar. These similarities would be something akin to how you might have similar appearance to a parent because of genetics. In this case would be similar spiritual energies.