WARNING: The following contains spoilers for X-Factor #4 by Leah Williams, Carlos Gomez, Israel Silva, VC's Joe Caramagna, and Tom Muller, on sale now.
Ever since the nation of Krakoa was formed, bringing him close to achieving his dream of mutant prosperity, Professor Charles Xavier has been acting differently. Throughout the "Dawn of X" relaunch, it's been obvious that the Professor is colder and more ruthless, and this has led to questions about what his current goals are and whether they're really in everyone's best interests.
The Cerebro helmet that he has worn almost constantly since the relaunch serves as a visual reminder of his change. It makes him appear less personable and therefore less trustworthy, and it also conveys the more firm, aggressive stance he has adopted. So when the helmet was knocked off him and damaged in X-Factor #4 it was a powerful message of the severity that the threat Krakoa is facing in "X of Swords".
The Cerebro helmet is the seventh version of the telepathic amplification and mutant tracking device which Forge made portable for the Professor. Since donning it when he announced the creation of Krakoa to the world, Xavier has rarely been seen without the helmet on, which makes sense given the vital function it serves for the nation. In addition to amplifying Xavier's powers to locate mutants, the new Cerebro creates telepathic copies of the minds of every mutant. These "backups" are used to transfer a mutants' personality and memories to a new body if they need to be brought back to life via the Krakoan Resurrection Protocols. Given this, the Cerebro helmet, and the five other models stored at strategic mutant locations, are arguably Krakoa's most important tools, which is why it was so alarming when it seemed like they may have been compromised.
In the second chapter of the "X of Swords" crossover, Xavier and the Five attempt to resurrect Rockslide and Rictor after they were killed in encounters with the forces of Arakko. While Rictor's resurrection is seemingly successful, the new body for Rockslide is defective and his personality doesn't match the original Rockslide. Xavier's attempt to restore his memories sent a kind of psychic shockwave through him, his Cerebro, the other models, and the Five, which was so strong it physically knocked Xavier's Cerebro from his head and damaged it. Hope Summers and the rest of the Five surmised that since Rockslide died on Otherworld soil the realm's other-dimensional properties corrupted the resurrection process and because of this, any attempt to connect with his mind damaged the Cerebro network and possibly the current crop of resurrection materials. The resurrected Rockslide is not the one the X-Men know but an amalgamation of his doppelgangers from various alternate universes. Since Rictor did not die until after returning to Krakoa, he was not affected in the same way.
Xavier appeared without Cerebro for the rest of the issue. Just as the helmet's presence serves as an imposing visual, the absence of it now conveys a degree of vulnerability that encompasses the entire mutant race. Except for one storyline in Marauders, this is the first time in a year in which mutant lives have been in genuine jeopardy and calls in to question Xavier's leadership capabilities.
Despite the mutant nation being in the most vulnerable position it has experienced in its young history he resolves to go ahead with the plan to send sword-wielding champions into battle against Arakko's own, a decision Quiet Council member Emma Frost chastises him for. Despite the recent devastating events, Xavier still believes he can control everything to go according to whatever his mysterious plans are. But his ego may very well be blinding him to the possibility that Arakko and Otherworld are too much for him to handle and it might him and all of Krakoa.