Maces can be stacked in the midline because (once again) all the weight is in the head; so it’s more likely to shift and fall to the side far away as you see in the picture above. Another common question is, “do I switch hands?” Yes for both, always switch your grip to perform both sides by switching your hands (which I constantly state in all my videos with maces & clubs for all exercises).
So which one and what can you do with them?
To make this clear, one is not better than the other. It more so depends on YOUR fitness goal and what can best suit your needs. Personally as a example, I started out with the steel mace first and glad I did because I had a separated shoulder injury when playing football years ago. What was interesting about the mace when I first got into them was I could press a 106lb/48KG kettlebell, but could barely perform a 360 with a 10lb/4KG mace at the time. This made me realize I had a huge shoulder imbalance going on. The mace favors fluidity and control all at the same time. This is why I constantly state the 360 is at the center of the steel mace universe (just as the hardstyle swing is at the center of the kettlebell universe). The mace 360 is where you vertically stack the mace by grabbing the base with both hands at a stable 12 o’clock position. Once set, you push the mace around you’re shoulders letting it swing into a pendulum behind you and then pull mace back in toward you’re belly back at the 12 o’clock position. This simple movement grooves the shoulder girdle, strengthens the upper back, and is essence of control. So warming up with 360s made a huge difference in performing kettlebell snatches, pull-ups, and presses with my shoulders feeling less ratchety. So if you feel you're moving more and more like the tin man before your workouts — the mace is the oil to bring smoother movement patterns: