So here are some pictures. First up, to the right, is the pattern for the V8804 sleeve. I've drawn the seam lines on the pattern (in orange) and pinned the pieces so they are oriented correctly at the biceps level. I also shortened the sleeve because I have short arms. I haven't tried to true it up afterwards.
The weirdness of the sleeve is caused by the exaggerated curve of the front sleeve piece no. 12, and both pieces along the centre seam. When these seams are sewn the sleeve does not follow the shape of a person's arm when it is at rest. Look at your arm when it's at rest and your hands are at your side. The profile when seen from the front is more or less straight, or curves away from the hip.
Have a look at this croquis. It's exaggerated but makes my point. Your arm only curves inward toward your hip if you're posing with your elbow out. This sleeve wants to curve that way all the time.
Incidentally, I realized that I have the incorrect piece no. 14 which has apparently been corrected by Vogue in later printings. My piece is not graded for the different sizes and I gather it's the size 14. It's longer by about .5cm than it should be. No big deal, in the greater scheme of things.
The sleeve from V2770 can be seen to the right, and to the left I've put V8804 on top, more or less matching it at the underarm point.
The 8804 sleeve is approximately 4cm wider at the bicep.
The sleeve caps measure almost exactly the same along the seam line. The 8804 sleeve is designed with slightly less ease (4cm) as compared to the 2770 sleeve (5cm). However, the 8804 sleeve seems to me to need less ease because it also incorporates that curved seam down the middle. This makes room for the shoulder and arm. I think the 8804 sleeve cap could be improved by being narrower.
I was surprised that the two sleeves are more or less the same height at the cap. Based on how they look and feel I expected the 2770 to be higher and a lot narrower than it is.
I'm not a pattern maker and will be feeling my way towards redrafting the sleeve. I foresee lots more boring muslin sewing in my future. Any ideas you have will be appreciated!