When the player's character moves through a steep slope of the mountain, then his speed is reduced to a minimum. Please Note! I say ONLY about steep slopes! These moments annoy the player, because this point in the Arma3 is implemented poorly and not realistic.
At this moments, the character will just switched to standard walk-movement and keep the his arms ideally straight and motionless, like he continues to go at perfectly flat terrain. In the such conditions, not one man from our planet, cannot walk like on a flat ground and expesially keep your primary weapons in an ideal and fixed position. For this purpose, requires special animation in which the player's character will have to make some efforts with swinging weapons in the hands.
This movement animation will give a better sense overcome the hill slopes in the Arma3 and will looks realistic. Please make simulation of Arma3 realistic.