Claudia Campomayor Watt, 63, suffered critical injuries after she was allegedly stabbed in the back while working at Coles supermarket in Ipswich, southwest of Brisbane, on January 13.
A 13-year-old boy was charged with attempted murder and remains in custody to face court in February.
Coles stripped knives from sale at stores across Australia "out of an abundance of caution" as it conducts a review following the stabbing.
However, the Shop, Distributive and Allied Employees' Association (SDA) has called for all retailers to remove knives from the shelves and instead keep the utensils under lock and key.
"We put cigarettes behind the counter, we put spray can paints into locked cabinets so that people cannot come up and just grab them off the shelf," SDA Queensland Secretary Justin Power told AAP.
"Most major retailers put mobile phones and expensive items into locked cabinets.Â
"It is not too much of an ask to say these items for sale which can be used as a weapon to assault a staff member or a customer should be put under the same lock and key."
Under "Jack's Law" in Queensland, daggers, double-bladed weapons and tomahawks are required to be kept under lock and key.
The union is calling for the same treatment of kitchen knives across all retailers.
"The laws are good at helping protect our members but while knives are available on the shelves and easily accessible as a spur-of-the-moment weapon, they don't protect from random, unprovoked attacks," Mr Power said.
In Queensland and Victoria, shoppers must be over 18 to be able to purchase a knife in a supermarket.
Other states like NSW and ACT it is an offence to sell a knife to a child under 16.
Under the current laws, Mr Power said it doesn't stop a teenager from stealing a knife from within the supermarket to bypass the age check.
"You would be a fool to not realise that if they can't buy it and they're under 18 and they want it, they'll just take it off the shelf," he said.
Following the Ipswich stabbing and the rise of violence against retail workers, Mr Power said union members are feeling on edge.
"A lot of retail employees will be getting up for work and saying goodbye to their family and wondering if something is going to happen in their store," he said.
The union has asked for an urgent meeting with Queensland Premier David Crisafulli to discuss its call for greater restrictions on knife sales.
Mr Power said union branches across Australia are beginning to push state governments to enact change.
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