I asked the same question to Angie and her answer was, if I understood correctly, to choose blazers carefully, i.e. that the sleeves be narrow enough for scrunching. Or to have the item tailored. I pay attention now and I must say I do notice a big difference in blazers: some sleeves are simply to wide and will slip down again, which is very annoying.
The worse ones are those that will initially stay up, then slowly but surely as you walk slide down, while if you're carrying a large purse like I do all the time, tucked under my armpit, only one sleeve drops (the one from the free arm). It's impossible to discreetly push the sleeve back up because the hand that would normally do so is being used to stabilize the purse. I know it's very silly but I've pondered the problem many time walking to various places around town with one sleeve unfashionably dangling down, and the other up and exposing a lonely elbow and its forearm.
Body tape: yes but what do you do when you want to remove the blazer? And that happens. Rubber band: it cuts my circulation too. Muscles: I do work out, but my muscles never want to bulge out enough to make a difference... AJ I am very intrigued by the pony tail scrunchies you describe. What on earth is it? I visualize a Barbie ponytail of soft hair... I'm sure that's not it...
Let me add my own stopgap solution to the list. When wearing a shirt underneath, I like to pull the sleeves' cuff out and fold them over the blazer's. When style allows. It makes it stick up longer, as the shirt is usually cotton, not silk like the lining, and also narrows the sleeves.