There is inconsistency in how masterworking calculates and rounds. With most stats and items, the below formula fits and that’s how it worked on the PTR, however, it doesn’t fit the two scenarios with +skill ranks below. I’m yet to find anything else (but skil ranks) that doesn’t fit.
Legend:
X - base stat before GA or any other manipulations.
[ga] - +50% mod if GA is present. Calculated off of base.
N - number of MW crits/hits
[mw.crit] - sum of MW crits on stages 4/8/12 25% each
[mw] - sum of regular MW upgrades 5% each
Y - final stat after
Y=X + (X * .5[ga]) + (X * N * .25[mw.crit]) + (X * N * .05[mw]).
- Glove +3 FO skills, ranging [2-3], no GA, became +4 FO at 7/12 regular upgrades, no crits. I should mention, here the base +3 is rolled from Occultist (before 0/12)
- Glove +4 FO skills at base (with GA) became +5 on crit at 4/12 and stayed +5 even after 8/12 upgrades (second MW rolled on another stat).
P.S. How do I upload a screenshot of those two gloves?
Edit#1: Added spaces to * as they turned into Italic.