The 49-year-old blamed her resignation on stress caused by a lack of support from the head teacher and management at Tennyson Road Primary School in Luton. She said she planned to take her case to an industrial tribunal, claiming constructive dismissal.
Mrs Davies, a teacher for 27 years including seven at Tennyson Road, was removed from her infant class last November and asked to teach older children after she let Joe Middleton smack six other children on the hand with a wooden ruler.
At the time, she said that Joe, who has learning difficulties, had been kicked "like a football" in the playground by six boys aged five and six, and that she gave him the choice of forgiving them or smacking them.
She defended her actions to the school management and parents, and wrote to the Secretary of State for Education, Gillian Shephard, asking for her support.
When given a final written warning that she would be sacked if she refused to give a firm undertaking not to allow a similar incident again, she insisted she had acted in line with the school's anti-bullying policy.
Yesterday, Mrs Davies said she still believed she was right to allow Joe a chance to stand up to his tormentors, but would think twice before doing the same again.
She claimed stress had affected her so badly after the incident that she needed psychiatric therapy, and feared having to retire through ill- health.
Mrs Davies said: "The stress was down to the lack of support I got from the headmaster and governors and the fact that parents and teachers have told me they feel too intimidated to support me.
"I am afraid that the school management were not listening to me and accepting the truth of my intentions, which was to help a kid to stand up for himself."
The incident last October divided parents at the 160-pupil school. Some launched a petition in her support while others condemned her for contacting the media.
Her head, Graeme Russell, said yesterday: "Since she is considering going to an industrial tribunal it is not appropriate to comment further." Lucy WardReuse content