Before the blade can be used, a Shadowhunter must name it to invoke its power. Any angel's name, except for Raziel's, can be called upon. Within the Shadowhunter community, it is often believed that when a Shadowhunter names a seraph blade, the blade not only becomes engulfed by heavenly fire, but some of the named angel's spirit is infused into the blade as well.
Seraph blades are activated when their name is called. It is said to be stronger the louder the angel's name is called. Seraph blades are an efficient way to kill demons and Downworlders. When used against a mundane, the seraph blade has been observed to be vastly overpowering, causing the mundane to burst into flames upon the first blow.
Although they are chiefly for the killing of demons and rogue Downworlders, seraph blades are known to also affect angels. Ithuriel once used Jace's seraph blade to commit suicide on Earth and be sent back to Heaven. Seraph blades can also be used to create a Malachi Configuration.
Shortly after being named, the blades' power run out and it deactivates; in order to be used again they are sent to the Iron Sisters, which will recycle the blades. Also, during a fight Seraph blades can be "drowned" by too much demonic ichor and burn out sooner. However, they're useless against some targets or in certain situations:
- They disintegrate when used on the finalized version of Mortmain's mechanical automatons, despite the fact that these mechanical beings were run and possessed by demons.
- In Thule and in the lands infected by its essence, blades are unable to work just like every form of angelic magic.
- If they touch the armours of the Riders of Mannan, they'll explode.
- Sabnock's sibling was unharmed after being stabbed by a Seraph blade, probably thanks to the blood of Ash Morgenstern at its neck.
According to Shadowhunter legend in the earliest days of the Iron Sisters, when they were few in number and their Adamant Citadel was no more than a single adamas forge and a few protective wards, a lone Iron Sister was confronted with a Dragon demon in the Citadel. In her desperation, she picked up and pointed an unprocessed adamas jag at the Dragon, and prayed to the Archangel Michael, making the adamas unexpectedly burst to life as a sword. It bored through the Dragon's neck, engulfing it in heavenly fire. She then deduced what had just happened, and by the time her fellow sisters returned to the Citadel, she had drawn up the first set of plans for the seraph blades.
The seraph blades are, when deactivated, dull tubes with blunt edges. When activated, the blade springs to life, growing into a bright, glowing, dagger. They are clear as glass and are double-edged. They vary in length, from small ones like daggers, to long ones like swords. Although normally, they are two feet in length.
Known named blades
All the seraph blades ever called in the series, listed alphabetically, with the series book/s they were included in linked in the adjacent reference. For more angel names, go to the section on the separate Angels page.
- For some unknown reason, seraph blades cannot be named after Raziel. According to Luke, it just isn't done, while Jace said that it should not be attempted as legend says Raziel does not like it and it would likely result in "nothing good".
- Seraph blades are among the Nephilim tools rendered useless in "blighted" land by the Unseelie King's Black Volume of the Dead-derived magic.
- In the TV adaptation, Shadowhunters: The Mortal Instruments, the design for the seraph blade for the first season was the same as the one used in the film. It was redesigned for the second season.
- On both adaptations, seraph blades are not shown being named after angels. On the show, the Iron Sisters, while forging the blades, hear the angels whisper instead.