the edge is kept thick, before the HT, for 2 basic reasons:
- thin edge is likely to warp during the quench
- you need some beef to grind away decarbed layer, if one forms by mistake
With a good, sharp (ceramic) belt you can cut away hardened steel fairly
easily & keep it cool. Of course you must be careful not to overheat the hardened steel, as it will anneal it.
Some steels can take fair amt of heat w/o annealing much, but it doesn't take
much heat to anneal simpler steels - the 10xx., O1, W1 etc.
If any color forms on these, the edge will be too soft.