Ms Martin QC told the court she had been given instructions from her client, who had said he was willing for the hearing to proceed if he was not able to connect via video.
Mr Cray QC told the court that the Mr Justice Jacobs correctly found Brehmer lost control but did not follow through with that fully when passing the sentence.
The barrister submitted that Brehmer was "highly culpable".
He said: “We say that the overall seriousness of this case was artificially minimised.”
The offence was "very close to murder", said Mr Cray QC, adding that the sentence that had been given risked "lowering public confidence".