The others in the thread also gave very good tips, but here's my 2 cents as well.
Firstly, you can always turn the difficulty down to easy (assuming you're playing on Normal), or just visit the inn and hire a 6th party member (if you do, roll a melee character, which is what your party seems low on), which should give you enough advantage to comfortably kill the guy.
Alternatively, you can just travel on to Dyrford (assuming you managed to beat the Old Watcher and opened up the path) and pick up the GM, which is a great party member to have.
One more option is to just travel around a bit, do a few easy quests, kill some easy critters, and get that level 5 you're so close to. Then come back and royally hand Raedric his own buttocks.
Who is the Grieving Mother? I never met her.
Um . . . Also, I"m level 5 now. . . any other suggestions now that I leveled up? I always found it funny I can walk with full armor, no disguises after going through all that trouble to get in, in the first place. And the Priest of Berath gives you a secure inn to sleep in as well.