I recommend fresh character.
Your 2 handed heavy armored warrior would just not really fit in well trying to be sneaky and an assassin.
You could ABANDON your 2hand weapons and heavy armor.... but then... why not just start a new character?
Exactly. A new character is a great thing. Start fresh.
Exactly. No point in making one character do everything. By making a new character you get to start fresh.
Awesome

I'm actually in the process of finishing Mass Effect 1.
Then hop to it!
Oh, and you know how the story missions in ME1 are great but the side missions are generally horrible, with cookie-cutter hallways just mixed and matched to make "new" maps? Yeah, when I realized how bad the side missions were in ME1, I quit doing them (money is worthless, anyway) and went right through the story missions.
In ME2, however, you'll want to do ALL the missions, because they fixed it so they're all good. I'd be done by now, except I want to finish all the loyalty missions, and probably all the missions altogether, then finish the story.