Time manipulation

Please don't roast me if this is common knowledge but how can Seraphina hit as hard as she does if she just slows or freezes her surroundings. I mean sure they're slowed down but that doesn't affect how hard they are or anything especially since Uru-chan said herself in the questions she answered, that Seraphina slows or freezes others down and moves at a normal speed it's just that others are much slower than her. So like does she accelerate herself in time or something. Like I said I don't know if this is common knowledge.