As regards the accuracy, I believe the implication is that he's doing the millions of calculations per second to constantly adjust his actions to correct for environmental and physical factors to be able to reduce things down to a simple mathematical problem to allow for proper targeting. In essence, he's brute-forcing the problem to bypass not having years of physical muscle memory and practice.

As regards being able to move the mace itself, it's a simple matter of handwaved "momentum". It's a fairly common thing to run into in Anime in my experience, where someone is wielding an item that is too large for them to feasibly move and the explanation is given that they're able to compensate for the weight by "keeping the item balanced in motion", allowing a small force applied over a longer amount of time to impart a greater force. It's got some basis in reality — if you keep pushing a heavy weight across a floor, you can get it going faster than if you tried punching it, and the "hammer throw" sports event is based off of the idea of imparting momentum over a longer period of time — but it ignores two important factors of static friction and the material strength of the human body.

The first is simple. It takes a certain amount of force to start an item moving and if you can't get that first bit of force going, it's not going to budge. Ever tried to push something heavy and all you manage to do is have your shoes slip on the floor? That's because the force you're putting in is insufficient to overcome the static friction of the heavy object, so it instead gets routed into overcoming the static friction of your shoes. Your shoes get some dynamic friction, the force which opposes further movement of your body, but it's still not enough. Similarly, for a sufficiently heavy object, Amadeus is not going to be able to budge it. That said, as long as we're handwaving his "hypermind" accuracy, you can similarly imagine that he's finding ways to apply some small force to the object to reduce this coefficient of static friction. For a real-world example, if you can tilt that heavy object, and get it up on an edge, the static friction decreases as a function of surface area, making the object harder to pull.

The more difficult factor to overcome is the material strength of the human body. If you can apply a straight-line force, particularly when pushing, you can leverage the impressive compressive strength of human bones. Pulling on a straight line allows less power because you're limited by the tensile strength of the muscles and tendons connecting your joints. If you've ever hyper-extended a limb, you'll know how easily that can be overcome. If you have an object moving outside of a straight line, you suddenly have a host of other forces coming in at different angles, making the problem of using the most stable angles all the more difficult, and requiring that effort just to maintain the system in balance. Witness how someone participating in the hammer throw event will get exhausted if they just keep spinning in place because they have to exert effort to maintain their balance and continue the force.

So, in short, Amadeus Cho's feat of being able to lift, move, and throw objects such as the mace are improbable, but not entirely impossible, particularly as he is supposed to be able to think at such an accelerated speed to fully maximize his capabilities. In the real world, he'd likely only be able to do it once or twice before getting sidelined by all of the small injuries he'd be inflicting on his muscles, bones, and joints (all the worse for him because he's still growing, which means there's a good chance he'd be causing permanent damage to developing structures), but this is the comic books, a world where you can fall off of roofs, break bones, lose your spleen, and still be in fighting form a week later, c.f. the Batman family, so in a comic book world, I see his feats as plausible.

As regards the accuracy, I believe the implication is that he's doing the millions of calculations per second to constantly adjust his actions to correct for environmental and physical factors to be able to reduce things down to a simple mathematical problem to allow for proper targeting. In essence, he's brute-forcing the problem to bypass not having years of physical muscle memory and practice.

As regards being able to move the mace itself, it's a simple matter of handwaved "momentum". It's a fairly common thing to run into in Anime in my experience, where someone is wielding an item that is too large for them to feasibly move and the explanation is given that they're able to compensate for the weight by "keeping the item balanced in motion", allowing a small force applied over a longer amount of time to impart a greater force. It's got some basis in reality — if you keep pushing a heavy weight across a floor, you can get it going faster than if you tried punching it, and the "hammer throw" sports event is based off of the idea of imparting momentum over a longer period of time — but it ignores two important factors of static friction and the material strength of the human body.

The first is simple. It takes a certain amount of force to start an item moving and if you can't get that first bit of force going, it's not going to budge. Ever tried to push something heavy and all you manage to do is have your shoes slip on the floor? That's because the force you're putting in is insufficient to overcome the static friction of the heavy object, so it instead gets routed into overcoming the static friction of your shoes. Your shoes get some dynamic friction, the force which opposes further movement of your body, but it's still not enough. Similarly, for a sufficiently heavy object, Amadeus is not going to be able to budge it. That said, as long as we're handwaving his "hypermind" accuracy, you can similarly imagine that he's finding ways to apply some small force to the object to reduce this coefficient of static friction. For a real-world example, if you can tilt that heavy object, and get it up on an edge, the static friction decreases as a function of surface area, making the object easier to pull.

The more difficult factor to overcome is the material strength of the human body. If you can apply a straight-line force, particularly when pushing, you can leverage the impressive compressive strength of human bones. Pulling on a straight line allows less power because you're limited by the tensile strength of the muscles and tendons connecting your joints. If you've ever hyper-extended a limb, you'll know how easily that can be overcome. If you have an object moving outside of a straight line, you suddenly have a host of other forces coming in at different angles, making the problem of using the most stable angles all the more difficult, and requiring that effort just to maintain the system in balance. Witness how someone participating in the hammer throw event will get exhausted if they just keep spinning in place because they have to exert effort to maintain their balance and continue the force.

So, in short, Amadeus Cho's feat of being able to lift, move, and throw objects such as the mace are improbable, but not entirely impossible, particularly as he is supposed to be able to think at such an accelerated speed to fully maximize his capabilities. In the real world, he'd likely only be able to do it once or twice before getting sidelined by all of the small injuries he'd be inflicting on his muscles, bones, and joints (all the worse for him because he's still growing, which means there's a good chance he'd be causing permanent damage to developing structures), but this is the comic books, a world where you can fall off of roofs, break bones, lose your spleen, and still be in fighting form a week later, c.f. the Batman family, so in a comic book world, I see his feats as plausible.