Appearance and abilitiesEdit
The knife was described as common looking with short, dual edged blade, made out of two different metals. One side of the blade was made out of steel and had the edge so keen, it could cut through any physical material with negligible resistance. The other side was made out of what Lyra assumed to be the same type of metal used in intercisions (which would make it a manganese-titanium alloy) and was described to be "shade-coloured." This side of the blade had an edge even keener, narrow to the point neither a human nor panserbjørn (who was a master blacksmith) could perceive it with the naked eye, and had the ability to "feel" the gaps in the fabric of multiverse and use them to cut through the fabric, thus opening portals into alternate universes.
The handle of the knife was made out of wood and adorned with the relief made out of golden wire in the shape of an angel with spread wings on one side, and the angel with closed wings on other side. The wire was slightly elevated from the wood of the handle to ensure a firm grip on the weapon. The knife also possessed a special leather sheath with straps meant to hold the knife in place while not in use, as it could effortlessly cut through even the thickest leather.
No known material was able to resist the knife, although it was breakable, should a wielder attempt to use it whilst thinking about a person they loved. It was the belief of certain individuals that this was because the knife was incapable of cutting through love.
Due to this, the knife was broken on two separate occasions. Although Iorek was able to reforge it the first time, it altered the appearance of the knife. Its handle was charred from the forge fire, the blade shortened as the result of the smithing process, and left with the perpetual dark seams on the places where the shards were connected. Will considered the end result to be "ugly". However, the knife's abilities weren't impaired even the slightest as the result, as it was still immeasurably sharp.
The knife apparently held the ability to kill Spectres, as Will managed to stab one with it causing it to fade away.
The second breaking of the knife was purposeful, and left the blade of the knife in shards once again. It is unknown if the reforging has been attempted since.
The knife was made by philosophers of Cittàgazze, from the Torre degli Angeli, who cut many windows in their world. The full list of its bearers is unknown, but the first bearer known by name is Giacomo Paridisi, who won it in a fight with the previous bearer, and lost the two small fingers on his left hand obtaining it. He hid in the Torre degli Angeli from the insurgence of Spectres in his world, for many years protecting the knife. A young Cittàgazze man named Tullio tried to take it from him, but Lyra Silvertongue had been sent by Carlo Boreal to take the knife, and her new-found friend and companion Will Parry fought Tullio, prevailing, obtaining the knife, and losing the same two fingers in the process — marking him as the new bearer.
Lord Boreal and the Magisterium of the Church wanted to possess the knife because its ability to cut through any material threatened the Authority, who had survived the First Rebellion only because the rebel angels could not harm him with any existing weapon or material at the time (their fears were later confirmed when Will and Lyra used the knife to free the Authority).
Will and Lyra instead took the knife and used it to travel between their worlds for a long while, though the knife once broke when Will, trying to open a window, was distracted by the thought of his mother. The shattered pieces were collected by the two children, though, and repaired by the armoured bear and great metalworker Iorek Byrnison.
Iorek warned Will and Lyra that the knife had purposes of its own — indicating an intelligence akin to that of the alethiometer. He also indicated these purposes might not be good. Later, the angel Xaphania explained that Dust had been leaking out of the worlds through the windows made by the knife, and that, each time the knife made a window, it drew up a Spectre from the Abyss. Thus all windows leading between worlds had to be closed by the angels, except for one. Will and Lyra initially believed this one window could be between their worlds, but then realized that they had made a promise to the shades in the world of the dead: to leave them an opening so that they can leave it and rejoin the universe, by emerging into the world of the mulefa. Thus, Will realized he had to shatter the knife. As people in the multiverse are not capable of surviving for long outside their own universes, it was also necessary that Will and Lyra each return to their own worlds.
These are the rules that Giacomo Paradisi told Will Parry when he became the bearer of the knife:
- Never open without closing.
- Never let anyone else use the knife.
- Never use it for a base purpose.
- Keep it secret.
- Æsahættr literally means "God-Destroyer".
- Teleutaia makhaira means "the last knife of all".
Behind the scenesEdit
- It is possible that the knife may have been inspired by Saint Michael's sword in Paradise Lost, which was specially designed by God to cut through even the substance of angels.