Harry got paralyzed again when he specifically broke one of Mab's laws (regarding how the Fae deal with prisoners, I believe). The Mantle just completely left him, since he was rejecting acting like the Fae, or breaking Mab's will, or whatever.
This book, he was just really tired and injured a bunch. I think it's the difference between driving with a near-empty tank, and removing the gas tank all together.
The closest to de-powering Harry came in Skin Game was when the not-a-bigfoot stuck the nail in him. He had metal piercing him in Cold Days too, when Butters was operating on him after the faerie ambush. But when he renounced Winter law immediately afterwards regarding the disposition of Lacuna, his legs suddenly went out from under him.
It leads me to believe that the Winter Mantle and the healing of his spine are seperate gifts from Mab, and the one can be nuetralized like all powers, but the spine-healing is a whole other thing. When you get right down to it, the Winter Mantle is the price he is paying for the healing. The healed spine is his payment for taking up the job, while the Mantle is only the tool of the trade. It's like a cop's badge and gun. He can be disarmed by an adversary, or take a day off, or get suspended, all of which leave him without the gun, but he still gets paid, and is still eligible for his health insurance & other forms of remuneration. He only loses his pay (in whatever form) if he quits or gets fired. In Harry's case, saying "Screw Winter Law" was sort of like a cop quitting his job to break the law - he stops getting paid.
“Tolerance is the virtue of the man without convictions.” GK Chesteron
Inde muagdhe Aes Sedai misain ye!
Deus Vult!
*MySmiley*