The long-haired, neatly dressed, bespectacled former university tutor will long be remembered for his performance on the witness stand, as much as the terrible crime he committed.
He seemed to take on the challenge of beating a murder charge with the same gusto as the academic studies in which he invariably excelled.
But perhaps it was as much about his moment in the spotlight - a misguided attempt to impress people - as it was about dodging a murder conviction.
"There is certainly a sense that Mr Weatherston believed himself to be special, and is described as frequently needing other people's admiration," psychiatrist Associate Prof Philip Brinded said.
Whether giving evidence himself or seated in court listening to others, Weatherston frequently smiled or enjoyed a joke, while Miss Elliott's shell-shocked parents sat expressionless only a few metres away.
Whether the person portrayed was the real Weatherston, or a character suited to his defence, is unclear.
Certainly, psychiatrists who tried to get inside his head were convinced this was someone with genuine psychological issues.
They found no signs of severe mental illness, but diagnosed Weatherston as suffering from personality or anxiety disorders, and being prone to "narcissistic rage".
When he went to Miss Elliott's Dunedin home on January 9 last year, Weatherston says he did not intend to kill her.
Rather, he blamed his unique psychological make-up for him losing control.
He claimed Miss Elliott taunted and then attacked him with a pair of scissors.
There was little or nothing in the way of remorse.
His defence said it was his narcissistic character at play.
The most he conceded was that he "played a part" in the death and mutilation of Miss Elliott.
He spoke of her with contempt, saying from the time they met at Otago University in May 2007, she physically and emotionally abused him to the point where he could no longer cope.
"I was in a relationship and I wasn't going to be controlled. So I left it. That's all there is. There's nothing more to it. And now I'm free of the relationship."
Ironically, Weatherston had researched borderline personality disorders on the internet, not for himself, but in regard to Miss Elliott.
He painted her as a fantasist who saw the pair as the characters from Pride and Prejudice, Mr Darcy and Elizabeth Bennet.
Weatherston agreed he was frustrated with a trust set up at the University of Otago in Miss Elliott's honour and at her "contrived legacy".
"Clearly, I'm not Sophie's biggest fan because of the relationship we had and, in my view, she's an attempted murderer, or attempted a serious assault."
He told psychiatrists he was horrified and felt nauseous at the extent of his mutilation of Miss Elliott, as though someone else had done it.
Yet, he also gave an insight into his targeting of certain areas of Miss Elliott's body as somehow representing the "emasculation of the relationship" that he felt.
Prosecutors said it was much more simple: Weatherston hated Miss Elliott and he had told people this the day before he killed her.
Weatherston's lawyer, Greg King, told the jury "no-one is asking you to like him".
Even Weatherston's own lawyers seemed exasperated at times by his insistence in trying to manage the evidence he was giving rather than answer questions put to him.
Weatherston also seemed to derive satisfaction from sparring with prosecutor Robin Bates as he was cross-examined.
In response to Mr Bates accusing him of lying, Weatherston seized on an opportunity to respond: "Are you lying Mr Bates? Are you not telling the truth?"Weatherston had no criminal history before this horrific attack.
So, from where did this complex killer spring? He seems to have come from a typical middle-class Kiwi background, described by his family as "easy and happy".
Born and raised in Dunedin, Weatherston was the youngest of three children including sister Angela and brother Gareth.
His father, Roger, was an electrical fitter, who worked on Central Otago dams but was around most of the time.
Weatherston was closest to his mother, Yuleen.
The family sat in the public gallery through each day of the trial.
Psychiatrists noted Weatherston's dependence on his mother.
Even in his teenage years, when he went out of town on school sports trips, his parents would go with him and stay with him in motels because of his bed-wetting problem.
Mrs Weatherston was at a loss to explain what her son had done, as she had never seen any inclinations towards violence.
Weatherston's academic success began from early in his schooling.
From his primary school days in the Dunedin suburb of Green Island, through to his years at Kaikorai Valley High School, Weatherston was always at the top of his class.
He was dux of his high school, but was still "self-doubting" and says he felt pressure to go on to university.
After only two weeks enrolled at Otago University, Weatherston quit to pursue part-time study and got a job as a clerk at an accountancy firm.
Though seemingly set for an academic career, Weatherston branched out into unusual roles: an aerobics instructor and a statistician for the Otago Nuggets basketball team - and even donned a costume and pranced around Carisbrook as the Otago rugby team mascot, Shaq the Cat.
At university, Weatherston breezed through his bachelor of commerce degree with 24 out of 25 A+ marks.
However, he says his over-analysing made him ill, and he sometimes missed exams - perhaps the first signs of what a psychiatrist would class an anxiety disorder.
After continuing to flourish academically and taking on teaching roles at the university, albeit with his ultra-competitiveness leading to conflict with some colleagues, Weatherston started a job with the Treasury in Wellington in 2002.
Sophie Elliott was due to start a job at the same workplace when Weatherston killed her.
Weatherston became ill with glandular fever in Wellington, and returned to Dunedin.
He sought medical help for anxiety and depression, and began taking the antidepressant Prozac.
Weatherston told psychiatrists he upped his dose of Prozac by three times before killing Ms Elliott, and psychiatrist David Chaplow said this could have played a part in the killing.
The first sign of Weatherston's capacity for violence against women may have emerged in 2006 when he admits he assaulted his then long-term girlfriend.
The woman told Dr Chaplow: "He won't forget anything that he construes as an insult . . . He can't move on".
"He is not outwardly crazy, but if you dig deep he has big psychological problems."
In the end, the jury did not accept Weatherston's problems explained his crime.
They saw what many others did: a cold-blooded killer.
