I have been wanting to reduce the draw weight of an old bow that I love to shoot but haven't been able to draw due to a shoulder injury.
So I measured out the limbs every 4", wrote down the measurements and started calculating a 15% reduction in the limb width. Marked out the bow and went to work. Between reducing the width, rounding the limbs and sanding the belly and back I have removed around 10lbs from the draw weight.
The key is to measure carefully and take your time. I went from 1.75" wide in the limbs and riser (TD B ow) to just under 1.4875" total width.
After re-tillering it shoots just as good as ever and now I can shoot it again.
P.S. the 15% reduction was measured and remarked every 4" to make sure I didn't go crazy with it.
Good luck!