Brendon Matiza, 26, was found guilty after a week-long trial at Oxford Crown Court of two counts of attempted robbery.
He previously pleaded guilty to count of possession of a knife.
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The jury heard Matiza held a knife up to two men in Garsington Road on August 2 last year, demanding they give him money.
A passing taxi driver intervened and allowed the two men to flee and call the police.
Officers attended and tasered Matiza after he refused to comply with instructions.
Matiza, of Leidon Road, Headington, will now be sentenced at the same court on April 19.