In Star Wars: The Rise of Skywalker, Rey announces that she is "all the Jedi" when reaching the end of her fight with Emperor Palpatine, but the moment could've been a whole lot stronger with one change. The Rise of Skywalker had to end both Disney's sequel trilogy and the Skywalker saga as a whole, and to help do so director and co-writer J.J. Abrams brought back Emperor Palpatine (Ian McDiarmid) for one last battle. Although many of the hows and whens with regards to Palpatine's return were left unclear by the film itself, it ultimately (and inevitably) boiled down to a final duel with Rey.
The final battle in The Rise of Skywalker wasn't just Rey versus Palpatine or even just granddaughter vs grandfather, but aimed for something grander still by making itself the culmination of the eons-long fight between the Jedi and the Sith. Palpatine, with the Sith Eternal crowd on Exegol behind him, declared that he was "all the Sith" and attempted to defeat Rey once and for all, after accepting that she wouldn't take his place and become the new Empress. In response, Rey says "I am all the Jedi" after having several Jedi voices call to her, lifting her up and encouraging her to win the fight, save the day, and restore balance to the Force.
Unfortunately, Rey's declaration doesn't quite pack the punch it really needs to in order for the moment to work. The proclamation itself is a little vague and perhaps even confusing to some, and while it isn't helped by some of the broader issues surrounding Palpatine's return, it would have been much better - and clearer - if instead of having Jedi voice cameos, there were actual Force Ghosts who appeared on Exegol. Given the list of Jedi who call to Rey when she's struggling and needs encouragement, there was the chance to bring back several beloved characters for one last go-around in the Star Wars franchise, including Yoda (Frank Oz), Obi-Wan Kenobi (Ewan McGregor), and Anakin Skywalker (Hayden Christensen).
The moment feels like it is literally designed to have Force Ghosts emerge - the Sith is on top, Rey is weakened and on her way to defeat, and the arena, filled by the Palpatine loyalists, is a darkened setting that could've been visually lit up by the Force Ghosts appearing. The idea of each of them appearing in turn - from the likes of Anakin and Obi-Wan to, say, Ahsoka Tano - could've been the sort of goosebumps-inducing moment that The Rise of Skywalker's final battle desperately needed, and would've provided more clarity in the moment too, giving greater context and meaning to her following "all the Jedi" line.
It would've had the added bonus of bringing back fan-favorite characters who are core parts of the saga, and deserve a true final farewell in a way that fits with lore established from original trilogy, and which is particularly lacking for Obi-Wan and Anakin (the latter not least given it's the Skywalker saga). It aims for this sort of effect when Lando Calrissian (Billy Dee Williams) and the calvary arrive in the aerial sequence, but this would've been its true moment of the heroes re-emerging, along the lines of Avengers: Endgame's portals sequence but blended with the sort of mythic quality seen in something like Lord of the Rings.
Disney's Star Wars sequel trilogy had already changed rules around how Force Ghosts work, with both Yoda and Luke Skywalker (Mark Hamill) interacting with the environments around them rather than simply being spectral presences, and that's something that could've been developed further (perhaps with the Force Ghosts forming a barrier around the wounded Rey). But even with the Force Ghosts used simply in their more traditional sense, having them physically there and being able to actually see them interacting with Rey would've made it a more tangible, powerful moment. The reasoning behind the Jedi voices in The Rise of Skywalker was to stay inside Rey's head - and no doubt it helped in terms of both CGI and actor availability - but having the Force Ghosts would've given the movie deeper connections to the entire history of Star Wars movies, and more heart as well.