(Video source [ x ] It's a featurette on the BluRay edition of the movie.)
It's rubbish as an actual fighting tactic, of course. The cross-body catch leaves his entire right side open. In a realistic fight, he'd have gotten either a fist or fuck-off huge metal disc right in the kidney, depending on which hand Cap had his shield in. (Mostly right, actually. Traditionally a buckler is on the left arm, but he uses his as a weapon as much as anything.) But it is very flashy, very impressive, and involves spinning the thing he's tossing around, which I have just this year discovered I can do.
(You're supposed to start juggling with rolled up socks or tennis balls, which I dutifully tried for many years; I have no idea where they're going or where I should be catching them, and they all eventually hit the floor and roll into the corner, where I forget about them. Fuck that. It turns out if I can spin things or flip them end over end, I can throw and catch them fine. I have no idea why it works, but it does.)
Also, I now have friends who will not develop nervous tics if I wander around juggling realistic prop knives. I have friends who juggle flaming torches, and set the extras on fire by transferring lit fuel with their fingers, if they're in a hurry. Stan's friends eventually started teasing him for constantly flipping around his props, on set, off set, at home, while driving. Yes, absolutely, make fun of the guy who's practicing to be a cyborg assassin to the point where he's actually good at it. That's an excellent idea! Either he really is very nice, or his friends really aren't that bright.
A lot of props can be surprisingly deadly, even the cheery ones. Ever played Soul Calibur III? Remember Tira? Creepy clown girl with teal hair and mad underboob? She fights with a hoop. The original has pointy wing bits on it, but one of her costumes in IV has a proper, candy-cane-stripe hula hoop instead. Gameplay clip:
She's terrible. I can hurt myself more efficiently with one of those damn things. Often without even trying! I've got some suspicious-looking bruises just above my elbows right now, because the other day I spent like two hours bouncing one of the big ones back and forth on my arms. The one she's using looks like it's probably 38" or so, between hip height and waist height on her, which is standard. A lot of trick hoopers use smaller ones, down to maybe 26", so they're easier to throw and juggle. Hula hoops, unless you have a weird custom order, are hollow inside; you can pour some rice or dried beans in if you want it to rattle as it goes around, or a cup or so of water if you want a sloshy counterweight, but in general they're not supposed to be that heavy.
I'm not sure it's massive enough to literally kill a man at the kind of speeds one can achieve with mere human arms, but I could definitely make someone regret fucking with me. Most of the bruise collection is just from the fact that you're using your body to push it around when it spins and it can dig in pretty hard, but I have dropped it on my foot more than once, failed to get out of the way in time and whapped myself in the thigh, and on very rare occasions, clocked myself in the head with it. I haven't given myself a bloody nose yet, but that's mostly luck. It hurts like a bitch.
Tira's not even really giving it a good swing. You can totally throw those things over your head two-handed and slam them down on something, like a bastard sword. The hoop will be fine; hoops bounce. (I don't like super-light hoops, in fact, because the smaller ones bounce so fast after hitting something they feel like they're chattering. Very disconcerting.) You'll put a good dent in your target, though.