Antonia's magic is split up. Before meeting Arill, Mizu, and Kai, she used pure magic, the most basic form of magic for anyone that awaited an elemental alignment. It is also considered in Dralan to also be the most powerful form of magic given the raw potential and purity of it. If she used too much, it would make her sick and weak for a good day or two, recovering in bed. The way she used it though was like it was like wind magic, the kind her father aligned with, so she always assumed that she was aligned to wind and air. She was late on getting an alignment for the fact that she is the Faerie Goddess.
Once her story is over, the different sage's blessings split up her magic evenly to all, but with the great fairie/goddess blessings, it gave her fire, water, and earth/nature magic an edge compared to the rest. So if she were to use Shadows, she would only be able to use a 1/6 of the power someone who's an expert in such magic could use. The fire, water, and earth/nature elements aren't greatly different, but it's better than using the rest power wise.
If she were to use them all at a go, that sick and weak thing would extend to a week then 1-2 days because of the boost of power the great fairies/goddesses gave.
There is a delicate balance upon becoming the Faerie Goddess for battle. The first thing is that she needs to have the magical capabilities to enter this mode, which drains her and leaves her to stay in bed to recover after returning from this mode. The other - and most important - thing she needs is emotional balance. If she is wracking around dark feelings and depression and it over powers the positive feelings, she will become not the Faerie Goddess, but the Lost Goddess of the Fey, where her specialty is Shadow and Forest magic and is emotionless; all she wants is destruction and nothingness. This can last for days on end, so long as L.G.o.F is in control, and after this she is stuck to recover twice as long as if she were the Faerie Goddess.
A side effect to becoming the Faerie Goddess is that her hair grows a lot from how long her hair becomes as F.G. It's how after her first time becoming the F.G. , she has her hair just past her shoulders.