Salford failed to reproduce the form which had beaten North Queensland Cowboys last week and which knocked Warrington out of the Challenge Cup earlier this season.
The Reds also had David Hulme placed on report in the 48th minute for the alleged use of his elbow on Jon Roper.
Lee Penny was forced to pull off an early try saving tackle on Scott Naylor and the full-back immediately supported a break from Vagana to touch down under the posts with a Lee Briers conversion giving Warrington a 6-0 lead after 10 minutes.
Warrington lost Mark Hilton after only two minutes with a shoulder injury and after Salford had a try disallowed by Naylor for obstruction the visitors opened their account with a Steve Blakeley penalty in the 22nd minute.
Paul Sculthorpe collected his neat kick ahead and fed Vagana who put Willie Swann over for his seventh try of the season and Briers added the conversion to make it 12-2.
An error by Finau conceded a penalty try to Darren Rogers just before the break with Blakeley's conversion giving Salford hope at 12-8 down at the interval.
Finau went over in the corner to give Warrington breathing space at 16- 8 before Vagana confirmed the win with Briers adding his third conversion and then landing a late drop goal.
Halifax's long losing run continued as they got no return from their long trip to the South of France on Saturday. A combination of weak tackling and a shortage of attacking ideas allowed Paris to complete the double, 32-0, in front of a 7,000 crowd.
"I was really happy with our performance," said a relieved Paris coach Andy Goodway after his side moved out of the relegation zone. "Everything went as we practiced. We played the numbers game."
Winger Phil Bergman opened the scoring, going in at the corner after taking Paul Evans's well-timed pass and Matt O'Connor added a penalty to his conversion to make the score 8-0.
Soon afterwards, Evans put Bergman into the same gap for the winger's second try before the big centre strolled through a gap to score himself and give Paris a healthy 16-0 lead.
There was no respite for Halifax, looking out of sorts in the heat and lacking the leadership of the injured Karl Harrison and the attacking flair of John Bentley.
After Halifax lost the ball, Bergman hurtled in at the corner for his hat-trick and a 22-0 half-time lead.
Seven minutes into the second half Pierre Chamorin took advantage of some weak tackling to put Jason Eade in at the corner.
Five minutes later, Matt O'Connor's pass sent in Anthony Hancock for Paris' final try, converted by O'Connor, which wrapped up the scoring.
Halifax improved their efforts in the second half but repeated earlier mistakes of failing to keep possession.Reuse content