Shardblades are mystical weapons. People who possessed a Shardblade were called Shardbearers, they are soul-bound to their blade until death, or until the blade is willingly relinquished.
Shardblades are generally associated with Shardplate, a suits of armor that complement the set.
According to legend, the Shardblades were first carried by the Knights Radiant, during the times of desolations. Gifts of their god, granted to allow 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. The are likely created in imitation of the Honorblades carried by the Heralds.
Four millennia later, they are regarded as priceless relics, wars are fought for them, and won by them. Each Shardblade was taken from one of the Lost Radiants after their betrayal. Dalinar's visions, showed roughly three hundred Shardblades were abandoned by members of two Radiant orders. Dalinar estimated, at the time of the War of Reckoning, there were less than hundred Blades in all of the world. Alethkar and Jah Keved owned some twenty Blades each and the rest were spread among the weaker nations including five Blades held by the Thaylenian royal guards. Selay and other kingdoms, such as Herdaz, had only a single Blade. Kharbranth and the Unkalaki people are not known to have any Shardblades.
Though Shardblades could cut easily through stone, steel, or anything inanimate, with very little if any resistance. They did not cut living flesh, its metal fuzzed as it passed through, without leaving a mark or spilling blood. It was said to sever the soul itself, leaving the eyes smoked and burned. For instance, 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. 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.
Shardblades were enormous, yet remarkably light. 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 blade, 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 blade until death, or until the blade is willingly relinquished. The process requires to simply pick up the Blade. Upon aquiring the Blade, it takes five days before the Shardbearer fully bonds to it, and is able to dismiss it. When the Shardbearer dies, the Blade rematerializes next to them, allowing anyone else to pick up the Blade and become its new owner.
Though each Shardblade is unique, there are in general two types of Shardblade. The first one is the type that are wielded by Sharbearers in the first and second books. They take 10 heartbeats to summon, have a gem in the pommel, and can cut through stone easily. When held by someone bonded to a spren, screams fill their head. The second type are ones wielded by Knights Radiant. They can be summoned when the spren are ready, can take any form (transformed to a spear, halberd, and shield during Kaladin's midair duel with Szeth), and have the same properties as other Shardblades. Syl mentions that the first type are dead spren after the first order of the Knights Radiants abanded humankind, which is why people that are bonded hear screams. In regards to Szeth's and Taln's "Shardblades," they are assumed to be Honourblades, as Szeth is not bonded to a spren and mentions them, and Taln was one of the Heralds who wielded them.
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.||Given to Sadeas|
|Elhokar Kholin||Sunraiser||Long and thin with a large crossguard. Etched up the sides with the ten fundamental glyphs. |
|Gavilar Kholin||Unknown||Six feet long with a design along the blade like burning flames. Silvery metal that gleamed and almost seemed to glow.||Unknown|
|Szeth||Unknown||Long and thin. Edged on both sides. Smaller than most others.|
|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. |
(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|
|Parshendi Shardbearer||Unknown||Wicked and barbed like flames. |
|King of Jah Keved||Unknown||Unknown|
| Shardbearer guard #1|
From Jah Keved 
| Shardbearer guard #2|
From Jah Keved 
|Sadeas||Oathbringer||(see Dalinar's Blade)|
|Knight (Dalinar's vision)||Unknown||Rippling steel, intricate carvings along the center.||Unknown|
|“||"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
- ↑ 7.0 7.1 TWoK Chapter 13: Ten Heartbeats, p.203
- ↑ 8.0 8.1 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
- ↑ 18.0 18.1 TWoK Interlude 9: Death Wears White, p.719
- ↑ 19.0 19.1 The Way of Kings, 9. Damnation
- ↑ TWoK Chapter 45: Shadesmar, p.643
- ↑ TWoK Chapter 52: A Highway to the Sun, p.731