The return of Kylo Ren's mask in Star Wars: The Rise of Skywalker could have been a lot better. In the original script from Colin Trevorrow, Kylo Ren's mask would have been brand-new and unique as opposed to the simply reforged version that was featured in the film. Not only would the mask have looked different, but it would have also resulted from a stronger character decision made by Kylo Ren himself when it came to his grandfather, Darth Vader.
Originally titled Duel of the Fates, Trevorrow's script was a very different conclusion for the Skywalker saga, and a big part of that was the darker journey for Kylo Ren. In Trevorrow's leaked Star Wars 9 script and concept art for Duel of the Fates, it was revealed that Kylo would have gotten his hands on a Sith holocron from the ruins of Darth Vader's castle (not a Wayfinder). Upon opening the holocron, the Sith artifact contained a message from the deceased Emperor for Lord Vader, instructing him to find the master of the Emperor's master Darth Plagueis known as Tor Valum, a 7,000 year old alien with knowledge of untold dark side power. However, the holocron explodes directly in Kylo's face, disfiguring him and causing great pain.
Ren would then be taken back to the First Order, and half his face would have been fused back together using Mandalorian beskar. Not only that, but Kylo Ren would have then donned a new helmet to cover his wounds. While it would have evoked the style of the first helmet seen in Star Wars: The Force Awakens, the script describes this new helmet as being "sharper, nastier. SCARIER." Additionally, the helmet would have had its own breathing mechanism akin to Vader's, although the sound of Kylo's breathing is described as being different than his grandfather's; deeper and gutteral. Likewise, leaked concept art provides a look at what the helmet itself might have looked like.
This is in stark contrast to what is actually seen in the officially released Rise of Skywalker from Lucasfilm and director J.J Abrams. While Kylo Ren does indeed venture to Mustafar, he simply acquires a Sith Wayfinder which leads him to the planet Exegol where the still-living Emperor awaits. Afterward, he simply decides to have the helmet he broke in Star Wars: The Last Jedi reforged using a special red iron to weld the pieces back together. Not only that, but he still chooses to honor the remains of Vader's helmet on a pedestal in his quarters. However, Duel of the Fates' Kylo Ren and his new helmet come from a stronger need due to his wounds and disfigurement that specifically came from the fact that he was not his grandfather, no matter how much he'd like to be.
Ironically, the holocron exploding in Duel of the Fates would have served as a wake-up call, leading to the realization by Kylo Ren that he wants to be greater than Darth Vader ever was, despite the fact that this new helmet would have made him look and sound more like Vader than ever before. Additionally, he would have cast aside and destroyed Vader's helmet, further signifying his determination to seek his own power. While this clearly would have been more of a dynamic reasoning behind the return of a helmeted Kylo Ren, Duel of the Fates was not meant to be. When it comes to his helmet, Rise of Skywalker's mask sadly carried less of an impact on Kylo Ren's overall development than it evidently could have had.