The kyubey of this universe has never seen a Witch before so the things that would make up a witch would look different from anything he has seen before.
That's irrelevant; Witches are made of Grief, which is something in the Soul Gem he understands and accounts for; what confuses him is that Magical Girls don't Witch out, but instead disappear. He doesn't know how a manifested Witch would behave but he knows what they're made of and how THAT works.
He's calling THIS a new color he doesn't understand, and it's not simply grief or hope; it's a new energy.
And yet Homura has no will to fight anymore if her will was stronger then the Wraiths her magic would not have been consumed in the first place, her own will is not why the wraiths cant eat the magic, the amount of emotions/magic is not why the wraiths cant change the magic my believe is that Homura's Witch is why the wraiths 'cant' handle her powers. If they are acting more like witches then its because a witch is involved.
Yea, Homura has no will after they removed most of her soul from her, go figure. Her willpower has nothing to do with them being able to TAKE the magic, since they can do that to anyone. They're unable to digest her magic.
Look, let me break this down for you. Wraiths are based on Buddhism. Their forms and attacks are named after terms, and they destroy emotions, which represent attachments in Buddhism, creating Desire and Suffering (Hope and Despair). They appear in the form of classical ascetics and are trying to force enlightenment on mankind by destroying their attachments.
Homura's attachments, her emotions and magic, cannot be destroyed. They can't break down her karma, her dharma, her ties to this world. Because the thing her magic is made up of is her attachment to Madoka. Her love for her, her memory of her. Her attachment to Madoka is her selfishness which keeps her from letting go.
And it's so powerful, a Wraith can't digest it.
It's so powerful, she became the Devil.
It's so powerful, that she became Mara, the devil who traps Buddha in an illusion of a happy universe to make him abandon Enlightenment.
It's because of Love that even Homura's pain is precious to her. So no, it's not 'a witch' that grounds Homura. It's the fact that she refuses to let go, and she has karmic associations with
GOD HERSELF. Homura entered the new universe with Madoka-tier levels of potential, and doesn't learn how to use it until the end of Rebellion.
She's already the Devil. She's already a godlike reality-warper, and the Wraiths can't handle it.
If they are acting more like witches then its because a witch is involved.
No, it's because Memory Magic is involved. They act like Witches for the same reason a Wraith acts like Madoka, another two act like Mami's parents, and another acted like Sayaka. They're using Homura's memory magic to imitate things in people's memories, and thus they behave like the antagonists Homura remembers: Witches. They're even able to use Time Stop because that's how Homura remembers her powers working.
Come on, dude. You have no case, here. There's no basis for your idea.