What a outstanding episode number 3 was! I was sad about Iwasawa..... and I like Yui sooo much!!! She's so cute^^
Angels comment about not being the bad girl made my head creating 100000 possibilities...

As for Angels powers, I have a theory:

Yuri and co. create weapons by remembering how they work from their life in Guild, no weapon can be created that isn't really remembered.
This was seen in Ep 2 where the large cannon aimed at Angel exploded, the guy simply said they didn't really remember how it works.

Okay so their weapons are limited by Earths boundaries of science....

Now for Angel, she seems to know alot more about the world, but she makes her powers the same way.
The world is a replica of a school on Earth so I guess everyone who is there thinks the same laws of physics apply as on Earth minus the dying.

If Angel however realized or just knows that the world is not limited by the normal laws of physics and if she trained enough I think she became able to just create stuff out of her imagination rather then knowing how it works from real life

If Yuri and co realize the same thing they should be able to have infinite power as the human imagination is in theory unlimited, it's kinda hard to explain what I mean, I hope you get it >.<