I had the pleasure of using Carols 240 and it was VERY reactive.
I own the 120 petty and gave it the same treatment that you did with yours.
I removed all of the KU, sanded the choil and spine and sharpened it to ridiculousness.
Removing the handle.
I found the easiest way to get it off was to clamp the blade between two 2x4's and use a block of wood and hammer to gently persuade the handle to come off. It was like a rusty nut - once you break it free it comes off easy.
The 240 more or less refused to take any patina.
I tried mustard's (french's and a store brand), vinegar, grapefruit juice.. and none of it took well.
The 120 on the other hand... it reacted to all of the treatments. I think what worked the best was heated vinegar. I just put it 100% strength into a sauce pain and brought it up to a boil.
I forced the initial patina so the blade was a bit less reactive. My 120 now has a beautiful natural patina and is far less reactive than it was at first.
George just returned my new Goko 150 petty.. and he used it to cut hot
beef and/or pork, and it looks great.
As for the sanding.
I sort of cheat a little on the spine and coil. I use a Dremel 520 Polishing Wheel
. One trick I've found with these wheels is to chuck it up and then take it to 120 grit sand paper; so it runs true. If you just put it in and go at the blade.. it will bounce all over and leave a weird pattern on whatever it is you're working on.
If sanding with paper(s).. I went to 800.
It seems to closed up the grain rather well and is certainly more comfortable on the hands. The only benefit you would gain from going to 2k is a slight increase, or delay in how the polished area reacts to ingredients. Steel is like wood, in a sense. The more you sand it and close the grain, the more difficult it is for ingredients to penetrate the surface. I agree it's a waste of time. It will soon patina and not bee seen anyway
If you're just going for smooth 320/400 is probably more than plenty.