Kamalgit Kaur was punched as she went to the aid of her nephew.
Mr Singh told the Herald he was in hospital for five days before returning to work after four weeks of recovery.
The wounds still sometimes caused pain - "for one or two seconds but normally it's all right" - but he tried not to think about the ordeal.
Aholima remains in the care of the Henry Rongomau Bennett mental health centre in Hamilton.
No trial date has been set.
Aholima's fitness to plead to the charges - which are wounding with intent to cause grievous bodily harm and aggravated assault - is yet to be determined.
It is understood the investigation into the allegations he had an affair with the doctor who treated him is continuing.
- additional reporting: APN