The hosts started brightly as Dunlop forced Dunne into action on seven minutes, with the Swifts stopper blocking the close-range effort with his feet.
Dunne was certainly the busier of the two keepers in the early stages and was forced to field a Wardell effort on 15 minutes.
Wardell was provided a real attacking threat for Crusaders, and he was inches away again on 29 minutes when he found space before curling an effort wide of the far post.
The Swifts struggled to impose themselves in the final third with Adam Glenny's cross, which dropped just wide of the back post on 37 minutes, the closest they came in the first half.
The visitors came out for the second half with their manager's words ringing in their ears, and they should have edged in front three minutes after the restart as Leo Alves picked out Gael Bigirimana inside the six-yard box, but the captain headed over with the goal at his mercy.
Alves then tried his luck from outside the box with Shea Callister pushing his shot away for a corner before he drilled a low ball across the face of the Crusaders goal which was just begging to be fired home.
There was a massive talking point on 67 minutes as the Swifts were reduced to 10-men after Dunne was given his marching orders for catching Wardell with a high challenge.
Referee Declan Hassan consulted with his assistant before showing the keeper a straight red with Alex Henderson coming on in goal.
The hosts made their extra man count inside seven minutes as Weir got on the end of a short corner routine between Wardell and Dunlop to head into the far corner.
The Swifts tried to muster a response but another short corner routine with three minutes to go saw Rough rise highest to head home the second.
Crusaders weren't done just yet as with the last kick of the game Anderson fired home from the edge of the box after Henderson miscued his clearance.