Thanks for the replies so far!
Looking forward to that video Frosty!
Ok so simple answer sounds like I should just leave it alone. I don't want the metal to bend when I put heavy torque on it. I can make do with the angle as is but it is not ideal.
Part of me thinks that the steel is beefy enough that it would function even if softened. In my experience the different qualities of steel make the most difference right at the cutting edge of the blade where it will be striking rocks frequently. An inferior steel at the cutting edge quickly mashes, bends, or I've even seen steel separate into two layers.
That being said I have seen a planter torque the shaft right off the blade.
Klorinth, from your description I wonder if this antique isn't what you were describing with "bare root shovel". I bought this thing for $5 off an old guy who collects antique stuff. I really feel like the quality of the steel is almost certainly going to be much higher than anything I can buy new today, that's why I went out of my way to hunt this down. I'm still trying to decide how I want to shave it down, whether I keep the kickers etc.
Canada goose, how would I go about testing? I imagine heat up with a torch in one are of strip of scrap, then let it cool, place in vice, torque the steel and see if it bends in the heated area first.
Thanks guys. I appreciate the enthusiastic responses.