It pained Seiya to see that she couldn't see what he saw.
The prince believed she had some semblance of good in her but he couldn't argue what she said about circumstances.
He wasn't too naive to think he knew better than others but he still couldn't agree with her intent on taking over the east for whatever reason she may have.
He couldn't trust what she had in store and the fact she was so willing to kill them already made her seem all the more dangerous to him.
Mifuyu was tired of waiting, she could see Shoichi busy collecting massive amounts of killing force and that Yir still tried to break Tsukumo free from his cage.
Giving them any more time was a gift that she preferred not to give and because of it she started to resume the fight by charging at Seiya with a certain degree of velocity that made the air around her become a force strong enough to send the prince flying before she even reached him.