The ex-Bloemfontein Celtic man was joined on the scoresheet by strike partner Kermit Erasmus in a consummate display by the CAF Champions League finalists at Orlando Stadium.
After the game, the Buccaneers were drawn to face SuperSport United in Tshwane in the semi-finals of the domestic event on November 20.
Bucs' fierce rivals Kaizer Chiefs, who they visit in the League on Saturday, will enjoy home advantage in the other last-four tie with Platinum Stars on November 2.
Pirates dominated against Abafana Bes'thende from the onset, and took an early lead as Bacela headed home Khethowakhe Masuku's right-wing cross 11 minutes in.
Man of the Match Bacela turned provider in the 34th minute, as he headed another telling delivery from Masuku towards Erasmus, who volleyed into the far corner in emphatic fashion.
Bacela struck again in the 42nd minute after smartly converting a through ball by Oupa Manyisa.
Bacela got his team's final goal with a simple finish in the 57th minute, with Erasmus providing the assist.
The hosts continued to press in the latter stages, with Erasmus in particular coming close to heaping further misery on Arrows.