Weatherston (33) stabbed the 22-year-old honours student to death on his 32nd birthday, January 9, last year.
He admits the manslaughter of Miss Elliott but denies a charge of murdering her, the defence contending he was provoked into losing control by the emotional pain of the relationship.
The Crown says the number of wounds - 216 - and the pattern of injuries indicate a controlled attack with a clear intention to target and disfigure areas of physical beauty and attractiveness.
Yesterday was the fourth day of the trial before Justice Judith Potter and a jury of eight men and four women in the High Court at Christchurch.
Evidence from Christine Haig, an administrator in the economics department, was she had a brief conversation with Weatherston on January 4 last year and he told her had moved on from a "bad relationship" and felt good about that.
January 4 was her birthday, Mrs Haig said and she knew Weatherston's 32nd birthday was on January 9.
There was a year between their ages and she jokingly suggested that perhaps 32 was an age when it was time to grow up.
He agreed, saying it had been "a hard year" but he felt good about having completed his PhD.
And he told her had moved on from "a bad relationship", which Mrs Haig knew was a reference to Sophie Elliott.
He assured her the relationship was really over and he was moving on.
He wanted to do some new things like learning French and Salsa dancing.
Weatherston told her Sophie had damaged his property and he was going to have nothing more to do with her.
Mrs Haig said she had not previously had any conversations with him about the relationship with Sophie.
On January 9, she saw Weatherston briefly about three times but did not talk with him.
She had written "happy birthday" on the whiteboard beside his door and was going to talk with him when he came in between 9am and 10am but he was on the phone.
She later saw him in the tearoom with a young woman she assumed was a marketing student.
The last time she saw him was about noon when was heading for the lift.
He seemed fine - "There was nothing unusual about him," Mrs Haig said.
The court has heard Weatherston arrived at the Elliott family home about 12.15pm the same day and attacked and killed Sophie about 15 minutes later.
Cross-examined by Mrs Ablett-Kerr QC, Mrs Haig said her relationship with Weatherston had always been amicable but she had been aware of deteriorating relationships between him and some other staff members in 2007.
She did not know of the situation with Robert Alexander, the internal examiner for Weatherston's thesis and also Sophie's course supervisor.
During her conversation with him on January 4, the accused had seemed positive about having applied for a lectureship with the department.
Mrs Haig agreed she had seen Weatherston and Sophie being "flirty" with each other.
She had also seen them ignoring each other and was aware the relationship seemed to be one that was "all on" or "all off".
To Crown counsel Marie Grills, the witness said she became uncomfortable with some of Weatherston's attitudes and behaviour during 2007 and had discovered he had a rather more arrogant attitude to his colleagues than she had realised.
She had been upset about the way he had kept trying to get his own way in an allegation he made against another colleague over a plagiarism claim.
His attitude in dealing with that was "overly persistent and arrogant", Mrs Haig said.
A doctor who examined Weatherston several hours after the incident recorded superficial abrasions to his face, neck, lower back, and the front of the left knee.
There was also a laceration, a deeper wound, on the little finger side of the accused's right palm.
Nirangan Sharma said he carried out the examination at 6.15pm on January 9 at the request of the police.
An ESR scientist was also present.
Dr Sharma said he could not recall if he saw blood on Weatherston's face.
The laceration on the side of the right palm had been masked by blood, as were superficial injuries to the accused's arm.
No medical treatment was required or he would have provided it, the witness told Crown counsel Robin Bates.
