Police say the 12-year-old was trick or treating Monday at about 150 different residences in the Spryfield area of the city.
Investigators say the boy was going through his Halloween candy when he cut his finger on the blade, which was stuck in the bar.
Police say the boy went through several streets seeking candies, and cannot say conclusively where the blade came from at this point.
READ MORE: Manitoba teen finds blade in Halloween candy
Const. Dianne Woodworth, a spokeswoman for the police, said the sharp object was sticking out of the bar when the boy cut his finger.
She says such cases are very difficult to investigate and past cases have had to be dropped due to a lack of forensic or other evidence.