Mark James Dennis, of Tregear, in Sydney's west, pleaded guilty in March to 13 charges, including having sexual intercourse without consent, armed robbery and maliciously applying an explosive substance.
During sentencing submissions in the New South Wales District Court Thursday, the court heard how Dennis robbed, then raped the 26-year-old woman in front of her toddler as they walked home after Carols by Candlelight in Liverpool five years ago.
Dennis robbed the woman at knife point and threatened to hurt her son, telling her, "Maybe I should take you for a drive but I guarantee that if I take you for a drive that it will be an all night thing because I have some friends in a car and they aren't as nice as me. Would you like a big gang bang?"
He then raped her as her son watched, tied her hands and feet with rope, tried to glue her eyes shut before pouring gunpowder into them and igniting it with a cigarette lighter.
Another of his victims, a 16 year-old girl, was walking home from school with her 10-year-old brother when Dennis lured them at knife point into a nearby park.
He put his hands down the girl's pants and then forced her to masturbate him before tying her and her brother with their school ties and fleeing.
In both cases, semen found on the victims' clothing or at the scene matched DNA from Dennis's discarded cigarette butts.
Wearing glasses and a dark suit, the former ice addict has gained weight since his arrest, Sydney Morning Herald reported.
In a statement tendered to the court, the raped mother said she felt as though she had been unable to protect her son during the rape and had trouble dealing with knowing what he had witnessed.
The other victim said her school work had suffered as a result of the attack.
"It has affected me and will continue to do so for the rest of my life," the statement said. "I just hope that one day I can forget about it altogether."
Judge Penelope Hock said she had never encountered such an offence in her 20 years of criminal law, adding that pouring gunpowder into a victim's eyes was a "completely gratuitous act which you might describe as torture."
She ordered Dennis to undergo a psychiatric report before a sentence is handed down in November.
Applying an explosive substance to a person with intent to burn carries a maximum 25 year prison term.
But Judge Hock said she will consider a discounted jail sentence because a guilty plea by Mark Dennis saved his victims the ordeal of giving evidence at a trial, ABC Online said.
The man remains in protective custody in Parklea Prison.