The victim, Mohammed Hanif, had been trying to intervene to stop mob violence in Montague Street, Brierfield, when 59-year-old Saeed Ahmed hit him with the stick.
In August, after earlier admitting assault occasioning actual bodily harm, Ahmed, of Montague Street, was jailed for 14 months at Burnley Crown Court.
But three senior judges at London’s Court of Appeal said the sentence was “manifestly excessive” and cut it to six months, allowing his immediate release on licence.
Mrs Justice Cox told the court Ahmed had been at the forefront of the trouble, because it was he who had felt aggrieved at an alleged insult in the street in May last year.
He went to a neighbour’s home with a group of friends and family to see the alleged perpetrator, assuring everyone that there would be no violence.
But the nasty incident erupted and, with many of those present wielding sticks, bats and other weapons, one man, Mohammed Altaf, was stabbed.
It was then Mr Hanif tried to intervene as a peacemaker, but was thanked for his efforts with a crack to the head from Ahmed’s walking stick.
Sentencing him, the crown court judge said Ahmed had taken a leading role in the group and made assurances there would be no violence.
But lawyers representing him before Mrs Justice Cox, Lord Justice Aikens and Judge Martin Stephens argued the sentence was too long.
The offence was not the most serious type of ABH and his personal circumstances - including diabetes, heart and kidney disease and previous good character - justified a lesser sentence.
Mrs Justice Cox said: “In all the circumstances, we agree the term of 14 months’ imprisonment imposed was manifestly excessive. We shall, therefore, quash that term and substitute a term of six months’ imprisonment.”
As Ahmed would only serve half of his sentence in custody before release on licence, the decision means Ahmed is immediately eligible for release.