Who is Kharu from The Covenant and what is their importance?

Kharu is Gumsto's wife. She is thirty-two-years-old and four foot seven inches tall. Her diminutive size, however, does not limit her influence. Kharu is described as a sensible woman with a whining voice irritating manner. Her primary job is to replenish the poison used to tip arrows.... poison that is admittedly strong enough to bring down an elephant. Khari teaches Naoka how to gather posion and locate water, hoping that her training will allow her to be a good wife for her son, and thus, insure the future of the tribe.