If your hands are numb, you don't want a bar with no sweep. As you already indicated, you are putting too much weight on your hands, and not enough on the saddle. A no-sweeper will not help.
A riser bar with a 9 or 10 degree sweep is what you want. If your natural hand postion is a zero degree sweep, you are sitting waaaaaaay too close to the bar.
You also want to look for a smallish length stem - 100mm or less. Ideally, your LBS will let you try a few options to see what feels best for you. A short stem is more precise (ie. quicker) - but possibly "twitchy" in unexperienced hands on tough single tracks.
Yes, a smaller width bar is usually best for single track, but ideally you want a bar that is approximately as wide as your shoulders to allow optimum hand placement.
You may also want to try different saddle heights to alleviate some of your hand problems. Lowering the saddle 1/2" to 1" may help, as it allows you to sit more upright putting more weight on your butt, and less on your hands/forearms.
Again, see if your LBS will let you try some different stem/bar options.