Cere's lightsaber had several requirements, it had to be a single bladed saber with a custom hilt that could proportional fit into one third of the full staff length when rebuilt together. This meant is had to be slightly shorter than Cal's broken hilt. The final proportions also had to work with the customization system.
We also tied the lightsaber with Cere's design by repeating elements such as using a leather wrapped hilt that harkens back to her belt, emerald stones and a triangular shaped clip that echoes her necklace.