you know, I was thinking of what those weights can be made out of, depleted Uranium is the heaviest natural element, but it's still a little radioactive and rather soft to make weights out of. Lead is the heaviest element that's not radioactive, but it is still very soft, not to mention BOTH of these things are heavy metal toxins so the weights would simply be dangerous to touch or even be around. But if they were made out of lead and then coated in plastic or something that would prevent it from coming into direct contact with people then it might be safer, assuming they didn't rip themselves off the bar because of their weight...(again falling back on the whole too soft thing.) OH OH OH! How about Tungsten? It's a little lighter than lead but still really heavy and much harder. It might be a little brittle so if she dropped it they might shatter, but I think you can make a plate out of that stuff
Lead is perfectly safe to handle for brief periods of time. You wouldn't want to make jewelry out of it, but handing lead weights is no problem. Given that it's also about 700lbs per cubic foot, it looks like a good contender for the weights on Anvil's bar. The REAL question is what the BAR is made of, since ten weights on either side means a total of 8 tons(!) total. The bar is very well reinforced, but even a steel I-beam that width would probably be pushed to its limits to hold that much weight.
So people with natural superpowers look like parodies of the human ideal, but Sydney gets her powers from her orbs, I'm guessing a magical artifact of some kind, which is why she's normal...is that going to be a thing in the comic? Are we going to see more normal people getting their hands on some maguffin that gives them abilities?