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I've used badger hairs from a cheap brush like this. I soon learnt not to actually cut the hair. The damage is obvious with a loupe.

That's a USB m'scope but set low IIRC approx 20x.

You've only described the bevels tho.
Look closely in sunlight or a bright light. Check for any sparkling anomalies in the edge. My be a slight burr or microchips.
This was the edge I received....

Another thought. A loupe or microscope may help you also. After viewing my Iwasaki under the 'scope I figured it didn't need much work at all.

I'm surprised it's not popping hair now but sounds like you have a plan. You could start on the 12k maybe . :shrug:

Hate to tell you but the Shapton 12 k you ordered is very abrasive ... for a 12 k at least.... so it is not the least abrasive manner for honing but it may be appropriate.
My question to you is how...