In the earlier pool match, Korea DPR defeated Brazil 4-2, to remain the unbeaten team in Group A.
Sweden striker Blackstenius bagged a double to make host, PNG, trail 2-0 at half-time, and added another double in the second half to increase her match tally.
Sweden substitute Johanna Kaneryd and Anne Anvegard also scored a goal each in the match.
The home girls failed to play basic soccer with many passes going astray, giving the visitors a stroll in the park in front of 9, 123 spectators.