Can you alter the nature of a charm? I didn't think it was possible, but maybe it would be if you understood the wording well enough. And I think you're right about it being a sort of hex. The effects weren't noticeable enough for it to have been a curse. In fact, I don't think I really noticed them at all until they were dispelled.

[Brief pause]

Looking back, I don't think everyone became aggressive at once, but I can't be sure. It all happened very quickly and I think I may have been a little preoccupied at the time.