Stigma are powerful magic abilities centered aound the user's eyes.
Magic Eyes
The Stigma are sometimes refered to as the Eyes of God, to others it is refered to as the Demons eye. Three known stigmas are seen throughout the anime series: the Alpha Stigma, Lino Doue, and Ebra Crypt. Torch Curse (a.k.a Tochi Kasu) is seen in the manga but not the anime series. The abilities of the last stigma (Will Hame) remain unknown; one can only wonder or imagine what it does. Also, the Alpha Stigma can only be activated when the user becomes enraged or when they have lost something important like the death of someone important.
Alpha Stigma
The Alpha Stigma
The Alpha stigma is known as a trait which happens in a rare few humans across the land of the series. It is the magic eye which is able to analyse and understand all magic. It is also posible for the Alpha Stigma to be able to anslyse structures around the bearer. For some weird reason, most alpha stigma users are driven insane by a close relatives death or a friends death. Which causes them to go on a rampage, making them seek destruction, killing and destroying everything around them. They seem to have a god persona, something which has to wreak havoc, until their body burns out and they kill themselves. Or what seems to be the case in some situations, they are hunted down for their eyes. Which are then "crystalized", in this case it seems to be where they disrupt the users eyes or mind and drive them to the edge of madness and beyond. [However Ryner is the only one known, whom is able to come back from the madness. - *consider possible revision; see below*] Due to The Lonely devil inside him.
Besides Ryner, there were two other Alpha Stigma Bearers introduced in the anime. Both of them were driven into madness as a result of the death of a loved one. The first one, Arua, was able to return back to normal after being knocked unconscious by Ryner. The second one, Pueka, had her crystal gouged out and died as soon as she broke down. In the end, Ryner was the only one that rampaged for longer than a moment, but this still begs the question of whether or not the book that Kiefer read--which made the claim that all Alpha Stigma bearers die after losing control without exception--is actually true or not. It seems that the author's conception may have been biased. Indeed, it is very likely that the author was a fearful human who considered Eye Bearers to be monsters completely incapable of controlling their power. Because Kiefer already knew that Ryner definitely did return back to normal without dying, she questioned the credibility of the book as well.* -Guest
The most probable reason for the Alpha Stigma to be more common is due to the nature of the Alpha Stigma. The Alpha Stigma's tendency to go berserk and kill in comparison to the other types might be the reason it is the only one so widely known.
Iino Doue
Lino Doue
The Iino Doue is able to devour the human lives, the bearers seem to have a lust for humanflesh as well. One whom uses the Iino Doue is able to absorb magic and absorb manna as well, from the fact the human body within the series uses magic in a manna base text. This ability seems to not have a point of insanity similar to Alpha Stigma, but the users have been shown to get pissed off when provoked, such as when Tiir was provoked and the children around him were killed by a known assassin (Since Tiir is the only significant character who has this ability, it may be it was just due to his own personality).
When a user of these eyes absorbs magic, or even life of people they can regenerate their wounds and become stronger, though they are killable and woundable. Iino Doue is one of the more rare stigma or eyes of god.
Ebra Crypt
Ebra Crypt is seen only once in the series. It has the ability to see into others dreams and the user seems to be able to access these dreams upon their own free will. Though it is said that most of the time the user will access random dreams of strangers, once they are able to access the dream of someone, it seems they are able to find his dreams again, as Ryner was told by the only user known to have this eye, who had been watching Ryner's dreams for a long while. However, bearers can only see fragments of the dreams they access, and it is never shown whether or not this eye can drive the user insane like the Alpha stigma does.
Torch Curse (Tochi Kasu)
While not having been seen in the anime, this type of eye has shown up in the manga. When activated, this eye stops the user's growth and development, so they do not appear to age, but their body 'decays' quicker. It appears as red birds over the bearer's eye, and allows the bearer to see into the future. Using this power appears to have negative effects on the body, as one user became blind (to present, she was still able to see future), apparently from overusing Torch Curse. With each use, the bearer's eyes and hair become more purple. It's the rarest of all stigmas.
Will Heim
The eyes of envy. Allows the user to see others' weaknesses and strengths, but causes the user to see themselves as inferior. Jealousy sets in and the user begins to hate those around themselves. They have a higher tolerance for other Demons Eye users, however. This stigma, along with lino Doue, can hear what Tiir refers to as 'God's Voice'.