Emma Lillian Rainbird, 21, of New Norfolk, was jailed last week after pleading guilty to wounding and assaulting her teenage sister.

Rainbird and the 17-year-old were drinking when the attack occurred a year ago in the defendant's home.

The couple had began arguing over the younger sister's sexual relationship with Rainbird's partner.

Rainbird swung a knife at her sister who moved with the blade puncturing a couch, the court heard.

The defendant then stabbed her sister in her right side, her palm and to the back of her head.

The victim went to the bathroom followed by Rainbird who kicked her in the stomach a number of times before somebody intervened.

When police arrived an extremely drunk Rainbird told them she'd "stabbed the little slut".

The victim was taken to hospital where she received staples to her head and stitches under her arm.

She required microsurgery on her hand.

Justice David Porter described it as a vicious and cowardly attack.

"It was not a case where in a spontaneous fit of rage you grabbed a handy weapon and attacked your sister," he said.

"You obviously made a considered decision to go into another room, get a knife, return to where she was, and without warning, stab her."

Rainbird was sentenced to 10 months' jail with the last seven suspended.