A Shardblade is a powerful weapon capable of slicing rock and severing souls. People who possess a Shardblade are called Shardbearers; they are soul-bound to each their Blades until death, or until each Blade is willingly relinquished.
Shardblades are generally associated with Shardplate; a suit of armor that completes the set.
According to legend, Shardblades were first carried by the Knights Radiant, during the times of Desolation. They were gifts of their Almighty, granted them to fight the Voidbringers, horrors of rock and flame, dozens of feet tall, whose skin were as hard as stone itself, making weapons of steel useless.
Four millennia later, they are regarded as priceless relics. Wars are fought for, and won by them.
Within his visions, Dalinar was shown roughly 300 Shardblades that were abandoned by members of two Radiant Orders. Dalinar estimated, at the time of the War of Reckoning, that there were less than 100 Shardblades in all of the world. Alethkar and Jah Keved owned some twenty Shardblades each; the rest were spread among the weaker nations, including five Shardblades held by the Thaylenan royal guards. Selay, and other kingdoms, such as Herdaz, had only a single Shardblade apiece. Kharbranth and the Unkalaki people are not known to have any Shardblades.
So far, no amount of fabrial science has even approached the possibility of re-creating Shardblades. However, recent rumors have claimed that Alethi scholars were close to creating new Shardblades.
Shardblades cut easily through most inanimate matter, so long as the blade is kept in motion. They do not cut living flesh; instead the metal fuzzes as it passes through, killing without leaving a mark or spilling blood. It was said that Shardblades sever the soul itself, the only indication of death being that the victim's eyes burned. Any part of the body that is cut dies instantly. If the Blade touched a man's spine, he died, eyes burning. If it cut through the core of a limb, it killed that limb, rendering that limb permanently limp, numb, and useless, however Surgebinders can heal limbs severed by shardblades by using stormlight. If a vital organ is struck, it will render that organ useless as well. However, once dead, flesh can be cut just like any other object. Also, parts of a living body that are made of non-living tissue such as hair, fingernails, and the shells of beasts are cut normally. A modern interpretation is that Shardblades can only sever nerves.
Shardblades were enormous, yet remarkably light. They were designed to fight something larger than another person. The large weapons took a great deal of skill to swing properly. There was never recoil; landing a blow felt nearly like passing the blade through the air itself. The trick was to control momentum and keep the blade moving. 
A Shardblade is summoned by the intent of the Shardbearer, willing it into existence, typically dropping into his/her hand extended to the side. The process of summoning takes exactly ten heartbeats (regardless of heart rate). When it materializes, the Blade is typically seen covered in water beads along its length, as if condensed from mist.
If a Shardbearer lets go of his Blade, it disappears unless it was willed to stay (which was a protection from being taken by the enemy during battle).
Shardbearers are soul-bound to their Blades until death, or until their Blades are willingly relinquished. The process for realignment requires of the new Bearer simply picking up the Blade, and, upon aquiring the Blade, it takes five days before the Shardbearer fully bonds to it (and is, otherwise, able to dismiss it). When the Shardbearer dies, the Blade rematerializes next to him/her, allowing anyone else to pick up the Blade and become its new owner.
Though each Shardblade is unique, there are in general three types of Shardblade.
The first is the type that is wielded by some Sharbearers in The Way of Kings and Words of Radiance; they take ten heartbeats to summon, have a Gemstone in the pommel, and can cut through stone easily. When held by someone bonded to a spren, screams fill their heads. (Syl mentions that this type of spren are dead - since the first Order of the Knights Radiant abandoned humankind - and that this is why people who are bonded hear screams.)
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The second type are those wielded by Knights Radiant; they can be summoned when the spren are ready, can take any form (i.e.: Syl and could be transformed into a spear, dagger, halberd, and/or shield during Kaladin's mid-air duel with Szeth. They have the same properties as other Shardblades, but unlike other blades, they glow certain colors from glyphs and symbols on the blade.
The last type, with regard to Szeth's and Taln's Shardblades, can be assumed to be Honorblades, as Szeth is not, and has not, been bonded to a spren. Taln was one of the Heralds who wielded an Honorblade. (In Words of Radiance, once Dalinar had become a Radiant, he heard the Blade screaming, hinting that it may just be a Shardblade). Honorblades are belived to grant some power over the paired Surges (i.e.: Jezrien's Blade grants Adhesion and Gravity; Nale's Blade grants Gravity and Division, etc.).
|“||'Dead,' Syl agreed. 'Then they live again a little when someone summons them, syncing a heartbeat to their essence.' ||”|
|“||'We're spren,' Syl said. 'We're forces. You can't kill us completely.' ||”|
List of Shardblades and ShardbearersEdit
|Shardbearer||Name of Shardblade||Description||Current Status|
|Dalinar Kholin||Oathbringer||Six feet long from tip to hilt. Long and slightly curved. A handspan wide. Wavelike serrations near the hilt. Curved at the tip like a fisherman's hook.||Hidden in Urithiru|
|Elhokar Kholin||Sunraiser||Long and thin with a large crossguard. Etched up the sides with the ten fundamental glyphs. ||With Holder|
|Gavilar Kholin||Firestorm||Six feet long with a design along the blade like burning flames. Silvery metal that gleamed and almost seemed to glow.||Unknown|
|Kaladin||Sylphrena||Kaladin's Honorblade is made up from his Spren Syl or Sylphrena. She can take any form that Kaladin needs her to. In his fight with Szeth she takes the shape of a sword, shield, spear, halberd, dagger, and warhammer. Anything he wants or needs her to be, she will be.||Alive with Holder|
|Shallan Davar||Pattern||Like Kaladin's, Shallans Shardblade is a bound Spren and does not require any time to come straight to her hand||Alive With Holder|
|Szeth||Unknown||Long and thin. Edged on both sides. Smaller than most others.||With Kaladin at Urithiru|
|Adolin Kholin||Unknown||Blue, one-edged blade. Sharp side is sinuous, rippling like an eel curving up into a point. Opposite side has delicate ridges, with the appearance of crystal formations. Six feet long. ||With Holder|
(killed by Kaladin)
|Unknown||As tall as a man, curved or sinuous, unsharpened side ridged with flowing waves of flame, etchings along the length, gemstone at pommel. ||Held by Brightlord Amaram|
|Eshonai||Unknown||Wicked and barbed like flames. |
|King of Jah Keved||Unknown||Unknown|
| Shardbearer guard #1|
From Jah Keved 
| Shardbearer guard #2|
From Jah Keved 
|“||Ten heartbeats, Return to me, you creation of Damnation.||”|
- It has been theorized that they are stored in the Spiritual Realm, when not used.
- ↑ 1.0 1.1 1.2 1.3 The Way of Kings, Prologue - To Kill
- ↑ The Way of Kings, 29. Errorgance
- ↑ The Way of Kings, 23. Many Uses
- ↑ The Way of Kings, 12. Unity
- ↑ The Way of Kings, 58. The Journey
- ↑ The Way of Kings, 56. That Storming Book
- ↑ Words of Radiance, 86. patterns do light.
- ↑ Words of Radiance, 87. the riddens.
- ↑ Words of Radiance, 87. The Riddens
- ↑ 10.0 10.1 TWoK Chapter 13: Ten Heartbeats, p.203
- ↑ 11.0 11.1 TWoK Prologue: To Kill , p.25
- ↑ TWoK Chapter 46: Child of Tanavast, p.648
- ↑ TWoK Chapter 13: Ten Heartbeats, p.205
- ↑ TWoK Chapter 58: The Journey, p.825
- ↑ TWoK Chapter 68: Eshonai, p.927
- ↑ TWoK Chapter 46: Child of Tanavast, p.661
- ↑ TWoK Chapter 1: Stormblessed, p.47
- ↑ TWoK Chapter 47: Stormblessings, p.671
- ↑ TWoK Chapter 51: Sas Nahn, p.704
- ↑ TWoK Chapter 69: Justice, p.930
- ↑ 21.0 21.1 TWoK Interlude 9: Death Wears White, p.719
- ↑ 22.0 22.1 The Way of Kings, 9. Damnation