some of the AA isnt really working, most obviously to me, on the bottom of the arm. The problem is that the dark AA color youre using there is so dark its nearly indistinguishable from the black, and so might as well not even be there. The 2 lighter AA colors are more noticeable, but are also so close to the lighter color they are AAing into that they are not very effective.
It would work better to just take 1 color that is about right inbetween the light color of the arm and the black and use that. You can also make the AA pixels "longer", each color of AA doesnt need to just be a single pixel, especially if youre trying to AA a line at an extreme angle, like in this example. You can stretch that color over 3 or 4 pixels if you need to.
I did an edit showing this. Then I added an extra image on the bottom showing how you could just add the AA color from the middle image, inbetween the AA colors youre already using if you wanted it even smoother.
