Hell Brand

The Hell Brand is a cursed seal only given to those deemed as complete enemies of the Chaos Knights.

Effect on the Bearer
The brand's effect on the bearer is rather extreme. If the person is not under the effect of a certain enchantment, or wearing an item with the same enchantment over the brand, it will cause extreme amounts of pain.

At first, the brand will only cause slight irritation, as if the person were scratching the area. The irritation will eventually increase and become minor pain, and at that point, the pain continues to double. Eventually, it will become so severe that the bearer will be completely paralyzed, his body overloaded with pain. The brand will also prevent death through this, torturing the bearer for all eternity.

Satoshi was given this brand two years prior to Path of Lightning. The glove he wears on his left hand was enchanted by the Chaos Knights as an experiment, though Satoshi was able to steal it. To this day, he wears it at all times.

Role in Echo of Thunder
In Echo of Thunder, the brand's effects are more extreme, as they begin eating at Satoshi's memories and emotions. This will sometimes cause him to go into a trancelike state in which he shows no emotion and reacts to very little. If this continues, it will eventually steal away all of Satoshi's emotions and memories, leaving him an empty husk.

Allusions

 * The effect of the brand on Satoshi may be why he boasts such a high defense, as the pain from the brand had at least tripled his tolerance for pain.