It seems that math is an obvious choice here. Working out gauge and
sizing and using stitch patterns that are a multiple of x or a multiple
of x plus y all require some basic math.
Reading comprehension is also required. You can't do knitting
patterns if you are unable to read and follow directions!
Physically, you are developing hand-eye coordination.
I think also there is some problem solving abilities required. You
can't always find the exact yarn so must substitute. Or you want to
make a size not presented in a pattern or somehow adjust the
pattern. You have trouble getting gauge and need to play around
with needle sizes and tension. Seems like all those things require a
fair bit of logical problem solving.
Just a few ideas!