I can now shape to this line from both sides and keep the cross section even. I used a combination of carving chisels and files to shape it.
I used an offset chisel and a parting chisel to remove the bulk of the undesired wood, stopping frequently to strop them on a two sided strop. It's important to strop frequently so you don't have to resharpen then saving you both effort when carving and saving your chisel. The strop finely polishes to keep an extremely keen edge. This strop has a linen side and a dense leather side, with a stropping paste applied.
After the carving I do final shaping with files. I use a cross cut bastard file, a cross cut fine, a combination half round rasp, and fine needle files.