So theres a mod called Melee Rebalance which lets your colonists use three modes for deciding methods of attack
1- Capture - Incapacitate them, don't kill them.
2- Disarm - Making them drop their weapon
3- Kill - Focus on killing them.
How about a shooting mod similar to this?
1 - Kill - Aim for head/brain, or vital organs
2 - Capture - Aim for legs/feet
3 - Disarm - Shoot their sword/gun out of their hand.
I can't think of the name but there are plenty of shooting rebalances. Please realize though that aiming for a specific part of a moving target isn't easy. I wouldn't count on any having that.
Shameless self-promotion opportunity (https://ludeon.com/forums/index.php?topic=28939.0); this doesn't have targeting modes, but it makes shooting skill more meaningful
Oh yah I forgot Xeo made one :/