Mac, you and I are on the same page
Differentially tempering blades: I do this with all mine. On a knife like this:
I heat the entire blade and handle to critical temp (what I'd describe as early orange-red, a touch hotter than cherry), then quench in used oil bath.
Then I gingerly wire brush the blade and handle to bare metal. A drop now ends the knife. Like you say, glass hard and fragile!
Now, I want the entire handle drawn to blue/purple, and the spine and tip the same. But I want the belly and most of the edge a straw colour. So, returning to the forge, I rake the coals flat, and tamp them down. Then I put the knife on top, handle only over the coals, until the handle draws yellow, brown, purple, then blue.
Now, I quickly grab the handle with tongs, turn the knife around, blade only over the coals, spine down, edge in the air. Draw temper until the spine is blue. If the edge begins to yellow at this point, I'll quickly cool the edge either by blowing on it, or dipping it in the oil for a moment.... Just the edge... And continue drawing the spine to purple/blue. Once the spine is drawn enough, if the edge isn't yellow yet, I'll turn the knife on its side to hurry that up. Stop at straw-yellow for most of my knives, brown to purple for fightin' knives.
I agree, quench is unnecessary following the temper, with the steels we are using (5160/1095, etc). Like others, I do it just so I can handle my new lovely that much sooner...
I love makin' blades... So much damned fun!
J