Some suggested answers:
The role of computers are therefore replaced by highly trained humans - in particular here we care about who replaced computers for navigating space ships, which is the personnel of the Spacing Guild. However, these navigators require the Spice mined from Arrakis to expand their minds to do that job. So whoever control Arrakis controls space travel... which also means that they can shut it down, and the entire empire falls, and the noble families lose all their trade wealth, etc.
Paul and the Fremen have the ability to destroy spice production forever, and with it galactic civilisation. So everyone concedes, because better a new emperor than losing everything.
Everyone has knives because shield technology exists that blocks fast moving projectiles and makes lasers unusable. However, guns and bombs etc. still do exist if desired - including orbital bombardments of nuclear weapons. So if you think in terms of the Fremen bombarding whole worlds from orbit, they wouldn't need to smash that many to rack up 60 billion casualties.
Besides, Paul is emperor. I don't fancy there's going to be that much organised resistance to his army except on a planet-by-planet basis, even if it's out of control and rampaging through the galaxy.
In the setting of Dune, computers and AI are strictly limited because of a revolt by sentient machines in the past.2. The ends on a little bit of an awkward note. The emperor surrenders, the great houses say "No", literally in the same scene they load up all the freman on ships to go fight a holy war and conquer the galaxy. This doesn't make any sense because A. The Great houses have the planet surrounded by warships, they could just blow them all up. B. How exactly are you going to take over the galaxy with a couple million troops.
The role of computers are therefore replaced by highly trained humans - in particular here we care about who replaced computers for navigating space ships, which is the personnel of the Spacing Guild. However, these navigators require the Spice mined from Arrakis to expand their minds to do that job. So whoever control Arrakis controls space travel... which also means that they can shut it down, and the entire empire falls, and the noble families lose all their trade wealth, etc.
Paul and the Fremen have the ability to destroy spice production forever, and with it galactic civilisation. So everyone concedes, because better a new emperor than losing everything.
The emperor is the emperor mostly because he has the Saurdarkar (spelling?). These are people who grew up on a hellish world which has made them as hard as nails and pretty much unbeatable, and so the emperor has the best army. The emperor also ensures that the militaries of all the other nobles are weak. If I remember rightly, one of the reasons the emperor sets out to destroy the Atriedes (generally they have become too politically respected and admired) is also that they have managed to train a small cadre of troops to be as effective as the Saurdarkar, and that is a definite no-no in the eyes of the emperor. This is also an attraction of the Fremen, because they also live on a hellish world, and have become as hard as nails, like the Saurdarkar.There's a lot more to it, or so I hear. That the galaxy is technologically weak, most of the great houses don't have much firepower. That said supposedly by the end of the war 62 billion people die. The numbers are difficult to digest. I looked around online, but everyone seems to say "yeah its just super vague, maybe Paul can see the future and win all battles...or something"
Everyone has knives because shield technology exists that blocks fast moving projectiles and makes lasers unusable. However, guns and bombs etc. still do exist if desired - including orbital bombardments of nuclear weapons. So if you think in terms of the Fremen bombarding whole worlds from orbit, they wouldn't need to smash that many to rack up 60 billion casualties.
Besides, Paul is emperor. I don't fancy there's going to be that much organised resistance to his army except on a planet-by-planet basis, even if it's out of control and rampaging through the galaxy.