Sorry it took me this long, but I missed this post.
This criteria is overly selective and it applies some restrictions of definitions that neglect the demon and put emphasis only on the mage.
Abominations are mentally unstable people and such persons are also non-mages who are possessed by very powerful demons.
You created a restriction on the definition of the word abomination that neglect the demon and put emphasis on the mage.
No I didn't. The definition I gave is the accepted one in-setting. And it draws a valid distinction between demon hosts who are more powerful than the demon, and demon hosts limited to the demon's own power.
I'm aware that during wars the veil become thin and that the thousands of dead persons don't always receive a burial,they remain on the battlefield and are hunted by demons who turn them into Revenants creatures that have nothing to envy to mage-abominations
A revenant is created when a powerful demon takes a corpse as its host. Lesser beings create mere skeletons. A revenant is powerful because it has a demon of pride or desire inside it, which is pretty bad. However, an abomination of pride or desire has the same power source as the revenant, and the mages' power on top of it. And that's why the Pride Abomination formed from Senior Enchanter Uldred and the Desire Abomination formed from Connor are the final bosses of dungeons with revenants in them.
In short mages aren't in circles because they are mentally unstable,they are there because they(especially when they are children)can do unconsciously harm to others like Wynne.
You're confusing my point. My point isn't that they are mentally unstable, so much as that mages increased tendency to meet demons can be compared to having a latent mental instability, and that when an abomination is created, it can be compared to a mentally unstable person finally cracking.
(And note that the above clarification shouldn't be taken to mean that there aren't some mages in Dragon Age who could do with some counseling. Just because magic and mental instability aren't the same doesn't mean that a bunch of characters don't demonstrate both. And lest people try to blame that on the Templars, two of the examples that come to mind are Quentin and Zathrian.)