Strength 1h is definitely great in duels, too. For the OP, I would put the points into shield or an offensive stat, unless you're planning for a later build with more bulk, then IF is fine.
Balanced is overall best, and it's only up to preference after 18 strength for which works with your playstyle. I have 25/15 with 56 body armor, and I take a good 3 solid 2h hits to kill. With good footwork and non-high damage 2hs, you're looking at 4-5 hits. Shield + IF combination is great, but low IF isn't too noticeable.
I used to be 27/12 a year ago, then respecced to 24/15 right when respec was released, and performed noticeably better. I reckon it will be the same if I went to 21/21 or some other similar pure melee build.