What class is your player character? Also, on what level are you playing? Normal? Hard? Nightmare?
Assuming your PC is not a mage, Wynne may be too underpowered for this fight, especially early in the game. Her initial setup is geared toward healing. You may want to skip this fight for now and come back later with a more potent team. This fight isn't necessary to complete "Broken Circle." And it may use up resources like grenades, lyrium potions, health potions, etc. that you will need for the final boss fight.
When you do decide to do this fight - or any Revenant for that matter - you should have a mage with the power to freeze him or paralyze him so that your tank can slice into him. I prefer using two mages - one a healer and another more lethally armed. Also, one archer rogue to pick away at him from a distance. One of the nice things about Origins is that you can make your warrior do dual duty as an archer. Aside from when your tank goes after a frozen Revenant, you want your team to keep its distance as much as possible for obvious reasons. You should always have plenty of health potions and grenades on hand as well.
By all means, report back whatever you decide to do. Always useful info for players new to the game.