None of the tests you can do by hand are definitive, the file test depends upon the hardness of your file. I had a hardness tester at my last job and my Nicholson Black Diamond files came in at around RC 63-64. My Heller files given to me from the company were 59-60. So if your blade was 60 or better the Hellers would just scratch the color off. I always aimed for a hardness of RC 59-60 for D2 and didn't worry if it tested 61, but my Nicholson would bite into it if I pushed hard, hard being the operative word. D2 is tough to file.
I learned to do D2 from Hinderliter HT company in OKC (for my job) and that is where I got the 425 temper from and I won't go into cryo treatments. As quenched D2 is around, at 1850 HT, RC 64 and I would guess from looking at the charts your blade would be around RC 61-62 with a 400 degree temper. Hope you have a diamond sharpener because you'll be there all day with any regular stones. If you use a belt to sharpen it, be careful, you can accidentally HT the edge (turn it blue) if you don't have a very sharp belt as D2 is very wear resistant with the Vanadium in it.
In retrospect I wouldn't worry about the blades being too brittle, but they are very hard. If you intend to sell the knives be forewarned that if the buyer doesn't appreciate a super hard knife he will bring it back saying it won't take an edge if he is using anything but diamond to sharpen it. But it will hold an edge for a long time and that is the purpose of an extra hard blade. Here's the link.
https://www.youtube.com/watch?v=woP1tqF-dsg