"I wonder how many people there are similar to you and I but less fortunate."

"Presumably about fifty times as many as there are of fortunates!"

"That irks me. Perhaps I'll find a way to give magic to people who don't starscape on their own."

"That would be really cool!"

"The fact that there exist both persons who want magic and are denied it and persons who are offered it and refuse it is subjectively offensive to me."

"I guess you seem like you have the powerset for it!"

"I am so pleased with my powerset." 

"Does it do anything besides identify magical girls yet?"

"I...haven't tried. The obvious extension from sensing magic is affecting magic, which..."

"...hm. Uh, do you have a sense for if it would affect a particular casting, or if it would affect the underlying magical properties of the caster?"

"...Let me think." 

She turns her attention to her magic sense, in particular scrutinizing her own magic as carefully as possible. 

Seems like that's up to her but affecting the underlying magic of the girl in question is going to be harder.

"I think I could do either in theory but the latter would be much harder."

"Okay, so you probably wouldn't do anything permanent by accident? Do you wanna have me try dropping-and-stopping stuff for you to mess with?"

"I wouldn't do permanent things by accident. I would enjoy trying that."

"Cool... I don't have anything handy I want to drop off a roof."

Katarzyna considers this for a moment, then plucks a feather off her wing. 

"That works! All right, whenever you're ready drop it and I'll stop it falling."

"Three, two, one," and then Katarzyna drops it, reaching out for the magic Isabella is about to cast. 

It stops in midair.

What can she do with this? 

She could cancel it, cause the feather to resume its fall!

Anything else? 

She could keep it in place even if Isabella let it go!

...Ooh. She tries that--

"Drop it?"