Slick

[bgosh]

  How would go about hardening a slick that is soft and will not hold a edge?

[Scoony]

Something of that size, I would search out a local knife maker and ask him to do it. Smaller sizes, I could handle with a make-shift forge, but not a slick.

[barryvabeach]

+1 with Scoony, that is a large blade.  If you can't find a local knife maker,  I have hardened 1/4 steel plane blades that were 2 1/4 inches wide, but to do it,  I needed to get some firebricks and form a sort of cave for the blade ( top, bottom, and sides were fire brick, with an opening for the blade in the front, and a small opening in the rear for the exhaust) , and it took 2 torches, and quite a bit of time to bring it up to temp.   The good news is that you don't have to heat the entire blade, probably the first half inch to inch so would be plenty, but you want to be sure the heat soaks into the whole blade, not just the top and bottom.