Hawke and Anders have experience, Anders was a Grey Warden, and Hawke is the PC, you think Merrill (who is already a blood mage) is going to refrain from using it? And then when someone snitches on her to the Templars....
Anders and Hawke are apostates who have no legal grounds to turn to if someone tells the templars they are illegal mages. Of course, Varric is likely protecting them both (since he's certainly protecting Anders) given his friendship with Thrask (per the short story).
LOL
I think the writing for the companions has been strong so far. Vivienne could also be a complex, three-dimensional character.
Dealing with demons in order to restore unknown and most likely incredibly dangerous technology, while disobeying the orders of her Keeper...
A gorram genius she is...
Merrill built the Eluvian based on lore she gathered and information she extrapolated from the shard.
She conspired with a demon, to open what could very likely be a portal to hell itself, in the middle of a crowded city. No wonder her clan wasn't too sorry to see her gone
Given that Marethari let Audacity loose because she thought that was true (and it's completely different than her initial reasons for opposing Merrill in Acts I and II), I wouldn't put too much stock in it. It's likely Audacity manipulated Marethari to be set free, and it worked.