«It is unclear how he died, but it's clear Nash feels some sort of heavy guilt related to him as seen in Tidal Locking, as when you fight or defeat him, he is seen as a mirror that can be shattered after wearing his hat, either meaning Xigeris was trying hard to be her so he can be accepted by the Rose Seekers and/or he turns into a mirror copy of Nash (when you do not wear the hat), as like she's fighting herself over his death. The fact you can find his hat in the hellish world of Bloxen probably alludes to the circumstances of his demise. It is also possible the presentation of Xigeris in Tidal Locking is not actually his true persona, but Nash's conception of it, as it is a memory world.»

Thing from wiki, that created this design. In my opinion, Darius could try to 'mirror' the way Nash dressed and behaved to be better than her even, though it's just a the fruit of Nashatra's strange memories...or just Xigeris reference for fun.