@Oiz nope i am sure its a VN
@doc_Kimble sorry it was a Japanese VN
i have thought of what i remember to. The have special weapons the can call with willpower. the classes are determined by their strengths in power. One Girl holds back with her power cos she do not want to hurt anybody due to her past. Another girl is really passionate to become stronger, and her childhood-friend is a blonde girl with the other academy and all of them and a childhood friend with low power but a good brain is although a love route. They train in a remote area. Some of the weapons a special heritage from past, where their ancestors slay an alien force invading earth. And a side charater has a power but whenever he uses it he becomes so exausted that he gets ill. and this char has a twin sister
Found it via Vndb... it is Koiken Otome, but its not linked at f95... sadly