No, No, No, NO!
THIS IS NOT HOW YOU MAKE KANNA BALANCED! IF ANYTHING, THIS JUST MAKES KANNA USELESS!
Kanna's normal M.Attack stinks in the first place, and Haku's blessing makes the damage actually do something against enemies and bosses. Yes it's OP if any other mage gets it, because almost every other mage has decent to high natural M.Attack damage. They're offensive. Kanna isn't. It's supportive.
Haku's blessing is seriously the class's best attribute to actually make it a decent class to solo/main. If anything, I would listen to almost EVERYBODY on this thread and make Haku's blessing only effective on Kanna, because this is the class that desperately needs it. Unlike most other classes(hint, hint, the classes that actually need to be nerfed), Kanna can't solo bosses without Haku's blessing.
Did anybody actually play Kanna in Nexon? Everybody who's ever played Kanna knows that their damage is horrible.