Customizing A Zanpakutō.

At first, as a Standard Zanpakutō, it will resemble a traditional katana and the only customizable part will be the cross-guard. From then on, Zanpakutō customization will wholly depend on the character's class and its current Release level; often drastically differing between Standard, Shikai, Bankai and Senkei. For Arrancar, customization of a Zanpakutō is wholly dependent on the level of transformation in Resurrection and Segunda.