I noticed that some of the classes got some really good skills that complement their weapons really well, others are just a bit ok and others does not really add something great to them.
The most left in the dirt class in this situation is the Grenadier, it's current class skills are mediocre at best.
Played with a grenade launcher, and i can safely say that despite the weapons having a wide AOE radius, it's effectiveness is really lacking in comparison to sprayer and sniper, whereas they can clean house way more effectively, even without their class skills.
Another thing that i really gripped on is that weapons have an all or nothing miss chance, if you shoot with an SMG 3 times in a shot, and the enemy miss or dodge, it count for all the 3 bullets instead of having a % for each bullet. The grenade launcher has it the worst though, as it has short range, low overall damage, can potentially destroy/hurt things outside the target area limit, even if sometimes you have 100% chance to hit it can still miss (Yes, it happened to me) and if the grenade launcher has the bad luck to shoot ever so slightly out of the targeted location, it miss literally everything, which does not make sense for an explosive weapon (Though the same can be said about grenade items), when you use explosive weapons it's supposed to be very destructive, right now it feels like a waste of weapon due to how the miss mechanic works.
Another thing i noticed is that class level up nodes has no benefits other than unlocking a couple skills, which makes it rather lacking in between them.
Suggestions:
Medic:
Make a Medic class, transfer the extra item level 5 skill from Grenadier to this new class;
Active skill: Attempt to Revive a deceased ally (Not a guaranteed success), only usable twice per mission;
Active skill: Give a temporary HP boost for a few turns to an ally (Cannot be targeted on self);
Passive skill: Always start with a Doctor kit (Medic specialized medic kit item) without using an item slot;
Passive skill: Guaranteed 100% regeneration on an ally who has been given doctor kit or medic kit treatment;
All these + the extra item passive from grenadier total 5 very useful skills for Medic;
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Grenadier:
Grenadier skill Shredder, replace with a Passive skill that allow 175% extra damage on cover, instead of being an active skill that nerf damage on enemies for double damage;
Active skill: Allow to shoot a single launcher projectile at double the usual optimal range (Like sprint for movement);
Active skill: Launching 3 launcher bullets, ignoring reloads in between at the cost of 1 total action (All 3 attacks can be made separately, but must be made in the same round);
Passive skill: Extra optimal range with launchers (Allowing for further range without losing accuracy);
Passive skill: Allow 1 No Cost Reload per round;
All of these + Shredder passive total 5 fully used Grenadier skill nodes and it won't fall behind as much;
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Sprayer:
The current skills the sprayer has are very good, so i would not change these two (Empty clip and No Action cost Reload);
Active skill: Apply Concentration status to the Sprayer, doubling their critical chance threat range for a few turns;
Passive skill: Once per enemy turn, if an enemy come 2 tiles close or closer to the Sprayer, the Sprayer can move 3 tiles away before the enemy act, should the Sprayer choose to;
Passive skill: Whenever the Sprayer shoot at an enemy, it has a chance to apply Suppressed status to the enemy, lowering their Action by 1 for the next turn;
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Assault:
Currently has 3 passives but no active skills;
Active skill: Unload the shotgun (Yes, shotgun only) completely at random targets within range and automatically reload, the first shot deal 200% damage and the 2nd shot deals 75% damage, low cooldown (Like 2 or 3 turns);
Active skill: The shotgun is loaded with a limited amount of explosive shells, each shot of the shotgun deal AOE damage in a 2 tiles radius and deals 150% more damage against covers;
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Sniper:
Currently has 3 passives but no active skills;
Active skill: For the next 2 turns, penalty to accuracy at close range is ignored;
Active skill: You shoot an armor piercing bullet with your Sniper rifle, damaging up to 5 targets/covers in a straight line, 200% damage against covers and 150% damage against enemies;
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I don't remember if there was other classes in the list as all my characters got all their classes chosen already and i cannot see it now, but those are what came up to my mind.
Additionally to passive and active skills, each node can increase the accuracy in the class's preferred weapons.