If you do an edge quench, the spine remains relatively soft, and no soft back draw is necessary. My process is to anneal a blade after forging, then do my rough grind, and then, when I'm heating the blade for edge quenching, I try to heat ONLY that portion of the blade that I intend to quench to critical.....then the only portion of the blade that hardens is that portion that gets submerged in the quenchant. Depending on the steel type I then temper for 3, 2 hour cycles, allowing the blade to cool to room temp between tempering cycles. You mentioned "toaster oven", which throws up a red flag for me. Toaster ovens are notoriously inaccurate....often swinging 50 or more degrees as they cycle. Every 25F will produce a difference in the steel's matrix...so if you're using a toaster oven to temper, NEVER believe the dial setting unless you verify it by other means.
This applies to MOST "forgable" steels....once exception that comes to mind is O1. All of the steels you mentioned...the information would apply to.
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