Board Thread:General Discussion/@comment-87.102.2.235-20160720090052/@comment-26397825-20161013025621

What if the Silver Eyes are a directional cone based effect when it comes to killing Grimm? So they only affect Grimm in the direction she is looking. In a horde, where she's desperate and Grimm are surrounding her in all sides, she could have activated her eyes and knocked a hole in one half, but the ones behind her escaped either marginally damaged (on the edges of the cone effect) or unscathed (outside the area of effect).

Then exhaustion from activating the eyes (even if it doesn't knock her out completely) plus exhaustion from fighting the horde could have hit, and the remaining Grimm overwhelmed her. So it's not a case of she didn't try to activate her eyes and wasn't super strong, but more the number of Grimm was just too high. After all, even the mightiest creature can be brought down by a hundred smaller predators.