Suppose Dickson had lived to publish Antagonist. Having brought the stories of Hal Mayne and Bleys Ahrens to more or less the same point, he would be poised to complete the series by writing Childe. What would that look like? To answer that question, let's reflect on the structure of the Cycle, and how often its past and future resemble each other. The most obvious example is Tactics of Mistake and Dorsai!, and how they're almost the same story, one played out against a background of recent interstellar colonization and one in the context of the mature Splinter Cultures.
Childe would have been the resolution of the battle between Hal, representing the outward-looking, creative part of mankind, and Bleys, representing our inward-peering, destructive side. We've seen this battle before in Necromancer, where Walter Blunt wanted to destroy complex, technological society to build something that to him seemed simpler and more natural. But that struggle between Kirk Tyne's vision and Walter Blunt's never becomes a war; instead, space travel allowed each one to pursue its goals, the technologists on Casssida and Newton, the mystics on Mara and Kultis, where, free of the need to battle stultifying over-mechanism on their own worlds, the Exotics turned from destruction to creation. That is, the thesis of the Super-Complex and its antithesis of DESTRUCT! are resolved into the synthesis of the Splinter Cultures.
Bleys is reminiscent of Walter Blunt; when faced with a society that he dislikes, his plan is to destroy it, and not let the collateral damage worry him. Bleys is generally seen as a dark version of Hal, but he's more specifically a dark reflection of Donal. Like Donal, he has a vision of the future of humanity that's rooted in his childhood. Both, by a series of clever tactics, gain near-supreme power in the universe in order to impose their vision on humanity. Neither realizes the essential instability of a system that depends upon one mortal man who has no successor of the same caliber. And both are responsible for the destruction of their brother/rival, though Donal is guilty of negligence and Bleys of malice.
Let's assume that Necromancer gives us a template for Childe. Some new development (in Necromancer it was space travel) provides a way for the thesis of Hal's faith in the human spirit and its antithesis of Bleys's pessimism about the dangers of the universe to become a new synthesis. What could it be but the Creative Universe, which is, in Paul Formain's words "Something to which your Alternate Laws bear the same relation alchemy does to modern chemistry." (Note also that to discover the Creative Universe, Hal has to join the Chantry Guild, which is based on a new reading of Blunt's original ideas. The connections to Necromancer are everywhere.) The essential difference between Hal and Bleys isn't only that they represent different halves of the race-mind; it's also that Hal, during the multiple lives that the Creative Universe has allowed him to live, has been able to develop empathy for and faith in humanity as a whole, which Bleys is still stuck in Donal's trap of needing to lead people to where he wants them to go.
One more point: in The Chantry Guild, the final bridge needed to reach the tower in the Creative Universe, which represents Hal's goal of understanding the Universe and mastering its use, is Tam's Newsman's Cloak. What does this Cloak represent? I suggest two things. First, Tam's conversion, so many years ago, from a purely destructive force to a positive one. Second, the essential function of a Newsman, which is to seek out the truth and make it known, but not to fight: Newsmen are recognized everywhere as non-combatants.
So, I think, the Creative Universe isn't used as a weapon against the Others; it's used as a means to persuade them, to educate them, and in particular to teach Bleys in one lifetime the empathy Donal learned in three and to remove the fear that motivates his destruction. Even to teach Bleys how to be, as he so desperately desires, Hal's friend.