Green’s Dictionary of Slang

brace n.¹

a drink taken as a pick-me-up, a ‘bracer’.

1881		Brooklyn Dly Eagle 24 July 2/7: A certain well known and brilliant writer [...] whose wel known form of invitation to imbibe is expressed by the words: ‘Let us take a brace’.
1890		Dead Bird (Sydney) 17 May 2/1: The actor stopped for a little ‘brace,’ / To got himself in trim.
1890		M.E. Ryan Told in Hills 183: They needed that swallow of brandy as a brace against the cold wind of the hills [DA].

SE in slang uses

In phrases

take a brace (v.) [SE brace, used of straps, belts etc that tighten]

(US) to pull oneself together, to smarten up.

1885		Democrat & Chron. (Rochester, NY) 9 Sept. 5/2: I think he is going to the dogs just as fast as he can. He [...] might take a brace [...] but he will go around with tramps and suckers.
1895		Rock Is. Argus (IL) 29 July 6/6: A Prophecy — Times are going to be better very soon [...] Let ‘us all take a brace‘ now, say things look healthy and they will be.
1899–1900		C.L. Cullen Tales of the Ex-Tanks 182: I told him he’d better hang on to his winnings and take a brace.
1907		W.M. Raine Bucky O’Connor (1910) 49: Cut out the water works, kid. You want to take a brace and act like a man.
1914		S. Lewis Our Mr Wrenn (1936) 163: I will take a brace, old man.
1918		Oklahoma Messenger (MS) 5 Sept. 4/2: A man who does not go to Church is in an unfortunate state. If you have been lax, now is the time to take a brace.
1922		Beaver Herald (OK) 26 Jan. 7/3: For heavens sake, take a brace. Treat people a bit decently, and they’ll think more of you!