"I had to walk to and from school past his house every day, frightened,'' she said.
The single blow left her with only "half my vision'', and had resulted in uncertainty over sitting her driver's licence and lack of focus at school.
She described Harmer as a "cowardly monster who gets thrills out of physically abusing females''.
"For my whanau to see me in that horrific state was heartbreaking ... my mana had been stomped on.''
She said she also felt "let down'' by police. "Why did it take four weeks for them to come round to get my statement?''
In court on Wednesday, defence lawyer Matthew Phelps said Harmer had problems controlling his impulses, particularly while intoxicated.
His client was "not sophisticated enough'' to function in a socially acceptable way, yet was "very upset'' when he learned of the victim's permanent injuries.
Harmer also admitted unrelated charges of assault and intentional damage, following attacks on Corrections officers and vandalism in Hawke's Bay Regional Prison and Manawatu Prison last year.
Judge Geoff Rea said he had a "dreadful record'' for someone his age. He claimed the charge laid was "unfortunate'', as a more serious charge would have been warranted due to the resulting wounding.
"As a result of that [lesser charge] the victim may not consider justice will flow from that,'' Judge Rea said.
"I am told you are remorseful ... [but] at the moment the only side I can see is the violent one who is for sentence today.''
He ordered reparation for the prison damage of $2477 and imposed a jail term of two years and three months.
While being led away Harmer gestured to the public gallery with a gang salute.
A police spokesperson rejected the victim's claims of police delays.
"A full statement was not taken immediately as she needed medical attention,'' the spokesperson said. "She was visited by police on October 17 where more details were taken and the offender was charged and appeared in court as early as October 27.''
