6dc5455c____The_Coppermind___17th_Shard__Entry
[Chapter] 36 [Entry] 
In Hemalurgy, the type of metal used in a spike is important, as is the positioning of that spike on the body. For instance, steel spikes take physical Allomantic powers—the ability to burn pewter, tin, steel, or iron—and bestow them upon the person receiving the spike. Which of these four is granted, however, depends on where the spike is placed. Spikes made from other metals steal Feruchemical abilities. For example, all of the original Inquisitors were given a pewter spike, which—after first being pounded through the body of a Feruchemist—gave the Inquisitor the ability to store up healing power. (Though they couldn't do so as quickly as a real Feruchemist, as per the law of Hemalurgic decay.) This, obviously, is where the Inquisitors got their infamous ability to recover from wounds quickly, and was also why they needed to rest so much.
The Hero of Ages/Epigraphs - The Coppermind - 17th Shard
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