A Lifelong Contract (Meimetsu Keiyaku) is how an Enchanted Blade stops being a tool you put down. It binds the steel to one body. The bearer’s innate sorcery, teleport, Flame Bone, Isou, whatever they were, shuts off for the duration. The sword is now the only language those nerves speak.
That is why Shiba never signs one. Teleportation is the practical magic of the series; a contract would take the exit away. Hiyuki’s Flame Bone is inherited, not a blade contract, which is why she can stand next to Enchanted Blades without becoming their employee. Hakuri’s Storehouse is clan sorcery. The people who pick up Kunishige’s wartime six give those arts away.
How a contract opens
Kill the bearer. The Hishaku spent three years on that plan. Hokuto murders Ibuki Misaka so Cloud Gouger can go to a customer. After Sojo dies, Chihiro briefly contracts the dying sword and spends its last Mei at the Rakuzaichi. A dead blade can still hold a few charges. It is not a new life. It is a leftover.
Samura’s specialty is the other door: cut the contract without cutting the person. What he does to Uruha looks like murder. It is Suzaku used as surgery, kill the knot, keep the man. That is why the Hishaku pact was never the whole file. See Samura and Tobimune.
The Magatsumi knot
Magatsumi’s contract is the master key. If Akemura dies, the other five wartime bearers die with him. Destroy Magatsumi and the knot comes apart. That is why nobody simply executes the Sword Master in the basement, and why Enten’s True Realm is not “beat the uncle.” It is the death of the blade that holds the others hostage.
Anyone who holds sheathed Magatsumi starts becoming Akemura. Kyora, dying, looks through the auctioneer’s eyes and sees the Master. Yura spends Shinuchi at range, then offers a body. The contract does not care about your job title. See Magatsumi.
Enten
Enten is still a Lifelong Contract. Chihiro’s innate art, such as it is, is the household: watching, copying, the goldfish. The contract does not shut a famous sorcery off because he never had one on the books. Nishiki’s resistance to other-blade ailments is the brief made visible, a contract written as a counter, not as a national weapon. When Magatsumi bisects Enten, the pieces stay with Chihiro. Suzaku-black stalls the rot. He starts notes for a new Enten like a smith again.
How the ten use the knot
Kill bearer, open contract, sell or spend steel. Hokuto applies it to Ibuki. The Sanso hits try it on the rest. Samura’s Suzaku is the other method: cut the contract, keep the person. Magatsumi’s master key (Akemura dies, the five die) is why the Kamunabi keep a monster in a basement. Destroy Magatsumi, the knot comes apart. Enten is outside the knot. Chihiro can sign a dying Cloud Gouger anyway; multiple contracts in one nervous system are legal in this book. Yukisada is not a contract problem. He is a barrier problem. Catalog of what the steel does once signed: techniques. Method: Hishaku.