The Nutaku version doesn't have that last part yet, so it might be a buff we'll one day receive.
What the Japanese wiki says is that her attacks completely ignore defense.
Specifically, it says:
20秒攻撃力が1.3倍
5体まで同時に防御力無視攻撃
For 20 seconds your offensive power is 1.3 times stronger.
Target up to 5 enemies at once while ignoring defense.
Compare that to someone like Spica and her awoken skill where it specifies she starts using magic arrows to ignore defense.
30秒攻撃力1.2倍
魔法の矢で防御無視攻撃
For 30 seconds your offensive power is 1.2 times stronger.
Your attacks ignore defense by using magic arrows.
Now, it's entirely possible that what it really means is that the attack converts into magic damage in order to ignore defense, and that it is just insufficiently descriptive, but just on the face value of the text it would seem like a physical attack that ignores defense.
edit:
Looking over skills even more, it seems like whenever they want an attack that deals true damage (like Claudia's dragon slayer or Sandra's cross slash) they say
防御と魔法耐性無視
Ignores both defense and magic resistance
or if the unit is clearly a magic user, like Solano, then it just writes that it ignores magic resistance since it's already apparent that they ignore defense by default.
It is just really weird and unintuitive for a physical damage dealer to have a skill say it now ignores defense but what it really meant is their attacks become magical and so now they are just going up against magic resistance instead. Magic swordsmen for example all have their actives state they ignore defense, but being that they are called Magic Swordsman it wouldn't be a stretch to assume that their active makes them magical.
If that's the case, it really would be a lot clearer if any instance where an attack is converted to magic to ignore defense to just say so and leave "ignores enemy defense" for a skill that is actually still physical and can bypass defense.