Willie the Duck
Hero
You could spend another NWP slot to raise the score by +1. It was incredibly inefficient, but they left open an avenue for it to happen.One thing to remember regarding NWPs and secondary skills in 2nd was that you weren’t supposed to be a master of these non-adventuring professions. Instead, your profession was adventurer, and that meant less time to master sculpting, obscure history, and so forth. Unlike the inestimable Dr. Jones, whose day job was archaeology professor, it was expected that adventuring PC spent most of their time and energy into exploring forgotten ruins, battling evil, and saving the town/kingdom//world/cosmos. That leaves little time for improving one’s skills at the forge. That’s the reasoning behind there being no increases beyond unlocking it or raising your attributes. The only ones who could improve were supposed to be retired adventurers.
NWPs in general are a double-edged sword for me, nostalgia-wise.
On the plus side, they really did give you an opportunity to make selections that differentiated your character from every other human fighter or whatnot, and I remember obsessing over the right combinations of them (and 'min-maxing' my character by choosing the right kit to get me two NWPs from my wish-list).
At the same time, the actual NWP system was a bit of a hot mess. Many of them were pulled straight out of the 1E Oriental Adventures and Wilderness & Dungeoneers Survival Guides with no revision or cohesive vision. Every facet of wilderness survival was split out into individual bits (because fine distinction amongst those skills makes sense for a Wilderness Survival Guide) -- meaning making a simple "warrior who can go out into the wilderness and live off the land" require 9 slot (Direction Sense, Fire Building, Fishing, Hunting, Survival(2), Tracking(2), Weather Sense; more if you want to Swim or be an animal-person or the like) - most of a no-kit, average intelligence warrior's career. At the same time, making a "scribe" require maybe 2 slots (reading/writing, and maybe heraldry), since no one had taken a keen interest in splitting out the finer details of that career path three years earlier. Likewise, a lot of the actual rules/subsystems for each NWP was not really built around use in-game (perhaps, as you point out, these are "non-adventuring professions") -- ex. swimming has rules for how many hours you can swim towards shore if you fall off a boat, but nothing about swimming in dungeon-water-trap situations. Most of the action (such as jumping) and survival-type skills do provide solid rules (although each their own subsystem), but a lot of them are so limiting or failure-prone (survival in particular taking special care to point out that relying on it "may lead to overconfidence and doom!") that the general message is 'don't put yourself into a position to ever need to use this.' I seem to recall much of our 2e gaming being us painstakingly choosing NWP to thematically differentiate our characters, and then absolutely ignoring the printed book rules for what they do, leaving it to DM fiat how they worked.