I cut a wedge at each underarm last night and sewed them back up.
It isn't perfect but oh, man, what an improvement! The sleeves "feel" better and there's a lot less bulk. I may have cut just a wee bit more than ideal, but this is all totally off the cuff and, given that, I'm thrilled.
I wore t-shirts a lot back in the day (these days, not so much), and ALWAYS with a cuffed sleeve.
Those original gigantic sleeves were a challenge, but the new version works great!
I also felled/embellished the seam. I chose Laced Double Straight Stitch in two colors from Natalie Chanin's The Geometry of Hand-Sewing -- it reminded me of "sound waves," and that was just about perfect for this project. If I were to do this again, I'd consider switching the colors (LEARNING THINGS)!
And now I want to add SIDE POCKETS! It's practically screaming for them, don't you think?