Right so your complaint is that she had no weaknesses and could kill anyone in one shot. 

Here's the problem with your reasoning: A lot of powers that inflict a direct attack will kill you. May it be lava, acid (very similar to Camille's powers), super fire attacks like Eli uses, and so on. Pretty sure a knife can one shot someone if stabbed on the body or head. 

You claim Camille had no weaknesses: 

1) Low stamina, she couldn't use some of her powers for very long. Only reason she lasted with Light was because Cedric failed very hard. 
2) Glass cannon, a simple punch to the face decommissions her. Shooting her with anything kills her. 
3) Let's face it, if you didn't purposely dick around you'd have beaten her easily. Not even a weakness, just a huge difference in power. 
4) Oh yah and she wasn't smart at all. She had pretty low intelligence, but good creativity. 

Don't pin this on me. Camille was totally fine with all the GM's. And never one complaint.