Long story short:

ArmA3 currently have 4 awareness stances in total.
2 for weapons lowered, 2 for weapons raised.
Each stance can have their own movement speed/pacing.
(They are by default toggled between by pressing Ctrl X2 or using Combat-Pace)

Currently, only the jogging animations make use of all stances and paces.
This method could in theory also be applied to the walking and idle animations to fill the gaps and create much more suitable stances.

Here is an example of the list for the current animations available when using a rifle. And what is missing:

[IDLE w/rifle]
1.Weapons lowered, Combat-Pace enabled (NO)(Same as anim 2)
2.Weapons lowered, Combat-Pace disabled (YES)
3.Weapons raised, Combat-Pace disabled (NO)(Same anim as 4)
4.Weapons raised, Combat-Pace enabled (YES)

[WALKING w/rifle]
1.Weapons lowered, Combat-Pace enabled (YES)
2.Weapons lowered, Combat-Pace disabled (NO)(Same anim as 1)
3.Weapons raised, Combat-Pace disabled (NO)(Same anim as 4)
4.Weapons raised, Combat-Pace enabled (YES)

[JOGGING w/rifle]
1.Weapons lowered, Combat-Pace enabled (YES)
2.Weapons lowered, Combat-Pace disabled (YES)
3.Weapons raised, Combat-Pace disabled (YES)
4.Weapons raised, Combat-Pace enabled (YES) {F23029}