Also agree on her using magic hammer too, kinda make her not looking good on her belief.
Just to point out she does not seem to use magic normally. You can see her in page 1 crafting a blade like normal. (Not saying whether she's a good blacksmith or not, just saying she does practice what she preaches)
She is
able to use magic, likely due to being an elf (we see another elf use magic at the festival and the kid also expects her to be able to cast magic), but, the way I see it, she does not value using it in her work because, to her, it removes an integral part of the art of blacksmithing, which is the time and dedication spent on crafting each weapon. She also says it's because it exhausts her after casting a spell just once, so she prefers hand making things. I think that's a valid opinion to have if you're an artisan.
To me this reads clearly as she is very passionate about the art of blacksmithing in particular and dislikes that magic ruined the market for traditional weapons, something she has dedicated her life to, as well as took away her enjoyment from the process of blacksmithing. She was likely being hyperbolic (who hasn't been when arguing back with mom or dad?) and she doesn't despise magic as a whole, nor does she literally want the demon king back, she just really likes traditional blacksmithing and feels frustrated that no one shares her passion.
The reason she uses magic at the end to craft a blade is because it's a do-or-die situation. She obviously can't hand-craft a blade fast enough in that situation so she used her magic for it. I think it's fair to give her some leeway here since she'd be dead otherwise.