Shield-Mount. As an Action and for 20 ft. movement, the Arbalist can mount or dismount its target shield on the ground, granting the Arbalist three quarters cover (+5 AC, +5 DEX Save).
Sharpshooter. The Arbalist doesn't have Disadvantage on ranged weapon attacks in range, they ignore half and three-quarters cover, and can choose to take a -5 penalty to the attack roll for a +10 attack damage.
Dwarven Arbalest
Ranged Weapon Attack: +8 (or +3) to hit, range 300 ft., one target. Hit: 2d8+6 (or 2d8+16 ) piercing damage.
Hamstrung Shot (Recharge 5-6)
Make a regular weapon attack and target must succeed a DC 16 CON Save or speed is halved for 3 turns or until healed (Hamstrung).
Through and Through (1/Short Rest, +BonusAct)
A greatbolt is released, causing all creatures within a 240 ft x 5 ft. wide line to succeed a DC 16 Dex Save or take 3d6 piercing damage.
Enchanted Shot (1/Short Rest, +BonusAct)
Make a regular weapon attack with Advantage and add 1d6 force damage on a hit.
Mighty Shot (1/Short Rest, +BonusAct)
Make a regular weapon attack and add 2d6 piercing damage. On a critical hit, the target is also knocked Prone.
Pushing Attack (1/Short Rest, +BonusAct)
Make a regular weapon attack and on a hit the target must succeed a DC 16 STR Save or be knocked back 15 ft.