How come in some mods like TomahawkThrowingAct when whatever you do, you land on your feet and keeps it in balance? What aspect of the game makes this possible?

its a mod
when you mod you can make the feets heavier so you can stay balanced.
in this case it isnt heavier, i just has downward thrust. see these lines of code:

body chest
thrust 1 0 0 1
body r_foot
thrust 1 0 0 -0.5
body l_foot
thrust 1 0 0 -0.5

so the chest is thrusted upwards so you can do a little jump before you throw the axes, and the feet have downward thrust so when you land youll stand in your feet.
hope this helped you.

I think I understand. So this is only created by mod making? Or is there a way for me to do this without mod making. Like....classic with downward thrust.

As far as I know, it's part of the mod itself, I don't think it's a changable option.

It's a mod, however you can mod classic to have this.

If all you want is balance, i can make you a classic mod with the heavier feet or that downward thrust.

@yoyo2009: Yes please. +rep by the time you give it to me.