You nailed it, seriously.
When I saw it at first I was thinking, "Dude that's the nicest parkerizing job I've ever seen. Then I realized it looked a little too hard-wearing for park and I thought, "He must have done something else and/or come up with some new finish!"
It's got the nice matte-look of park but it actually looks more durable from its visual presence, without being overbearing. I like Roguard, Black T, and black cerakote, but they all look too shiny, too "good" and not "traditional" in a sense, like parkerizing does.
Love it. I may well borrow your formula for the 1911 I'm planning to build for myself this winter!