Amusingly there is no record of rampaging blood mages or abomination in all Tevinter history. I'm not saying its a fact but its something to consider.
While I have no idea if it's canon or not, I like to think Tevinter has a great strategy for teaching mages not to become Abominations.
"Don't do it because it's ****ing stupid."
Practical Advice from a bunch of evil selfish guys.
Not "Don't do it because [insert religious reason]." which doesn't work if you're not religious and especially not when they say magic is evil in general because of religion.
Morrigan, for example, doesn't have to worry about becoming an Abomination not because of the Chantry because she knows it's stupid to become one and effectively suicide.
Merril too.