It wasn't actually fair to Einhart. It seems like this fight was what Einhart had been living for, and it turned out to be nothing like she had expected. However, for Vivio is was just another match against someone she hardly knows, like in some unofficial martial arts contest. Going all out with everything they had would have been what Einhart desired, not this match that would have seemed to favour Einhart from an outside observer's pov, but was flawed from her own.