Tom Jackson, 30, suffered critical head injuries in the attack by Frenchman Smail Ayad, 29, at the hostel in Home Hill, a rural town in the north of Queensland state.
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Fellow Briton Mia Ayliffe-Chung, 21, died in the incident late Tuesday, while a 46-year-old Australian man had non-life threatening wounds.
"There are many and varied reasons why we are, and always will be, immensely proud of Tom," Les Jackson said in a statement released by Townsville Hospital where his son is being treated.
"His actions in response to this horrific attack only add to that sense of pride."
Queensland police had said that Jackson's actions to help Ayliffe-Chung were "completely selfless... (and) led to the injuries that he now has".
Ayad has been charged with the murder of Ayliffe-Chung and is also facing two counts of attempted murder for the attacks on Jackson and the Australian man.
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He remains in police custody, with his case adjourned until October 28.
Police had said Ayad said "Allahu Akbar" (God is greatest) during the attack and again when arrested, but have also said there were no signs of radicalisation.
The Australian government has been increasingly concerned about extremism and in particular about home-grown radicalisation, keeping the terror threat alert level at high since September 2014.
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