Green’s Dictionary of Slang

(Aus./N.Z.) an axe.

1873		M.A. Barker Station Amusements 148: I had to get the tommy (anglicé — tomahawk) and chop his boots off.
1901		Bulletin (Sydney) 23 Nov. Red Page/3: ‘Good Heavens!’ says Pi, in a despairing whisper, and holds up to my view Alec’s cherished whip cut in half. She has done it with the ‘tommy.’.
1905		Bulletin (Sydney) 14 Dec. 32/4: ’I’m goin’ to fish out my tommy,‘ says Murty. ’That disgruntled son of a cow’s ’ad the loan of us long enough.’.
1923		J. Bowes Jackaroos 28: The tomahawk by all means. [...] You get the tommy and I’ll collar the billy.