The represents his Hollow and Soul Reaper powers. The smaller blade represents his Quincy heritage.
It is revealed that the "White" Hollow within him was his true Zanpakuto spirit all along. The "Old Man" admitted to suppressing Ichigo’s true potential to keep him away from the life of a Soul Reaper and the inevitable conflict with the Quincies. The Forging of Dual Zangetsu Bleach: Sennen Kessen-hen Episode 13
The episode’s central theme is the resolution of Ichigo’s splintered identity. Following the "Everything But the Rain" flashback in the preceding episode, Ichigo finally understands his complex lineage—born of a Soul Reaper father and a Quincy mother infected by a Hollow. This revelation recontextualizes his entire journey: The represents his Hollow and Soul Reaper powers
Ichigo discovers that the spirit he long believed to be "Zangetsu"—the "Old Man"—is actually a manifestation of his Quincy powers, bearing the likeness of a younger Yhwach . The "Old Man" admitted to suppressing Ichigo’s true
The episode concludes with a stark thematic contrast: while Ichigo achieves internal unity, his friend is shown joining Yhwach’s army, setting the stage for the "Separation" arc in the subsequent cour. BLEACH: Sennen Kessen-hen - Episode 13 discussion - FINAL
The episode’s climax occurs at forge. Unlike previous attempts where he lacked a true Asauchi (the base for a Zanpakuto), Ichigo now approaches the forge with a unified spirit.