With there being a need for her to capture Spirits rather than inflict harm upon them, the more offensive techniques seemed not to be so useful to her when she first began picking out what she would learn first.
They would help to wound or kill Spirits, but that way of doing things was too inefficient for her growth, especially with the way she had to do things.
It was still better if she captured the Spirits or Evil Spirits to bring them somewhere more secure and safe, where she could take more time to extract as much Life Energy from them as she could.
If she chose an offensive technique, then her gains for each Spirit or Evil Spirit might have encountered would not be so great compared to what she had been able to gain from the time she was able to use to extract Life Energy upon capturing them.
