[Snake]

1- Armament Weight being universal for Cannon skills would be nice. It'd also incentive Arbalests to build more STR.

2- Shore Up? True. It's such a flow breaker to have skills with awkward momentum costs, when every "action" in this game is 3M. So either go full 6M or reduce to 3M and make it have a longer cooldown.

3- Mighty Wall as a passive is a good idea. Having it just be something granted on round start that, if you move, you lose the effects. Similar (and synergizing with) Ranger's Expert's Aim.

Mighty Wall
Passive

Engage defensive mode, becoming a mighty wall for enemies to crash on.

At the start of a new round, gain Mighty Wall LV5 and Arbalest Countershot until your next round. If you already have Mighty Wall, the LV and duration are increased by 5. (Max. LV = 30)

Using any movement skill will cause Mighty Wall to end (while this skill is equipped), and this skill is put on a 3 round CD.

Mighty Wall (Effects)

Increases DEF and RES by LV.

If LV is higher than 5, immunity to Knockback effects.
If LV is higher than 10, immunity to Pull effects.
If LV is higher than 15, increases your chance to Parry equal to LV%.
If LV is higher than 20, immunity to Knocked Down and Airborne effects.
If LV is higher than 25, immunity against Rampaging and Burn effects.

4- Any Melee to be used with Arbalest for Armament purposes just makes sense, man. I don't know why it has to be removed. At the very least, make it have some form of Hit penalty when they're not the usual Sword/Axe/Spear, or damage penalty.

5- True that, it has no passive support for guns, even though it now welcomes them. Also, Rifles being highlighted compared to Launchers is a little sad. I think using a Jackhammer as an arbalest cannon would be way more fitting than an excel sniper, just saying.

6- With Shore Up being the "quickest reload" option for a hefty momentum and limitations on being used, a skill to accelerate reload every round would be a fine trade-off of momentum the Arbalest could be using to keep the assault going.