Introduction
So I've been looking for a mod to make Musketeer a bit better, cause I quite like her role and appearance (gives me vibes of Ashe from OW or Maia from PoE II) and I wanted to make her more viable and unique. Also, i felt like some of her abilities had not much sense and felt weird, probably because it's just a skin on Arbalest abilities. Anyway, vanilla Arbalest does suck as well.
But I found out that other mods either make changes that (I felt) differ her too much from her original design, or do not solve her problems, or just make her stupidly OP. So I said - fine, I'll do it myself.
So this is my own take on her. This mod aims to improve her kit, make her more viable and save (and reinforce) her role and design of the distinctive sniper-dps and support character. At the same time keeping her more balanced and unique.

Changelog with explanation

Equipment/Stats:

The Musketeer now deals more damage
1) 6-10 (from 4-8)
2) 7-12 (from 5-10)
3) 8-13 (from 6-11)
4) 8-15 (from 6-13)
5) 9-16 (from 7-14)

• So it's +2 DMG Low and High across the board
  

Her vanilla damage was just garbage, considering her SPD and reliance on marks and positioning, and especially for her other abilities that do not utilise her mark DMG bonus. Now it's consistently better and still not as high as HWM/Grave Robber or some other DPS, considering that they have either more SPD (Grave Robber) or do not require much of a set-up with marks, positioning and etc. She's also not as quick and flexible.
And I feel like it's in the theme for her as a sniper character to pump big shots.

• She also has less HP - 24-28-32-36-40 (from 27-32-37-42-47)
• But has more SPD - 5-5-6-6-7 (from 3-3-4-4-5)
• And slightly more dodge - 5-10-15-20-25 (from 0-5-10-15-20)
  

So my reasoning for this is that so much HP had not much sense for her as a backline character in a (seemingly from her art) leather armor. Which was okay for the Arbalest in her heavy plate armor, to be fair.
So now she has less HP - somewhere between HWM and Grave Robber and slightly (but not nearly as much) more SPD and Dodge - it's easier to move in a leather armor, after all.
Also, giving her more speed plays well into her role of a support + set up character.

• Crit Buff Bonus: +2 SPD (from +33% DMG vs Marked)
  

Crit Bonus for DMG vs Marked, again, was only good for her Aimed Shot and her role as a sniper, and did nothing for her as a support with cc and some healing. SPD is all-around more versatile option that is especially good for support, set-up and disrupt of the enemy, so she's able to react quicker (if someone is in trouble, before another enemy makes their turn, or bleed/blight will tick and finish someone on the team.) So now her good shots play better in buffing her second role, which is a good synergy between them.

Skill Changes:

Aimed Shot

• Now can hit rank 1.
  

Not being able to hit Rank 1 makes her feel clunky and makes little sense, considering that she fires from a backline (4-3 ranks), so its enough of a distance to snipe any enemy position. Also it makes her not just better, but at least puts her on the same level as other characters that can target any rank. This change also frees her from using other abilities that are less than optimal, just to hit rank 1. Other abilities have been changed regarding this, as well, so they provide something else, rather than just being able to hit rank 1.

• Pierces 20% armor
  

Just makes sense for the firearm, does almost nothing against enemy's backline, since they have no much prot and makes her a bit better against ranks 1-2 in conjunction with the previous change. Still has some room for the additional 20% pierce from HM/BH mark or from -Prot debuff.

Sidearm

• No longer random and can hit only 1-3.
• Now moves her back by one rank.
• Now has more ACC
• Now gives 2-4 SPD and 10-15 ACC for the next turn
  

This gives her an ability to make her way to backline in a sensible way. So you can take this ability not just for being able to hit rank 1 and gain some SPD, but to be able to reposition after a sudden shuffle/misplace/surprise.
Just makes sense to have for a sniper, especially more nimble and agile, than Arbalest (and reminds me of a similar move of Ashe from OW).

Call the shot

• Now also can hit rank 1
  

• Now can be used from any rank
  

So now more consistent with the other marks.

• Now lasts for 3 turns
• Debuffs a target for 5-10% Crit chance for 3 turns (same as MAA "Bellow")
• Buffs Musket for 1-3 SPD for 3 turns
  

Now has the unique mark debuff, instead of a -Dodge or -Prot debuff as do marks of the other characters. Dodge debuff from vanilla version was nearly useless for the Musketeer because of her high ACC, so it's always has been better to play her with other mark-characters like Houndmaster or Bountyhunter for -Prot.
So I made a new debuff that makes more sense for both her as the support and for the theme of her ability which is called "Call for the shot" - like it's addressed more to her team, rather than against the enemy, like "Mark of Death" (of BH) or "Vulnerability Hex' (of Occ).

Buckshot

• Now can be used from 4/3/2 ranks
• No longer pushes targets back
• Deals 50% less damage, but still full (+50%) DMG vs big enemies (vs size 2+)
• Now reduces enemy's protection (-10-20% Prot)
• And causes bleeding 2-4 for 3 turns
  

So I felt like the knockback had little sense for both Arbalest's Bolla (which in my opinion should rather debuff Dodge and SPD, or something), and the Buckshot itself, and also its been extremely useless to try and knockback these 2 targets, because it could cause them to just switch places and that's been weird.
As this ability simulates a shot from something like a shotgun (Buckshot is literally used as a shotgun shell which is better against a larger game IRL) and is already used against frontline, usually taken by big armored foes, I felt like it should be focused on specifically taking down these closer and bigger targets, rather than backline priority targets, as Aimed Shot does. So this distinction helps separate these two abilities, without making Aimed Shot useless against frontline enemies.
And since it also applies -Prot debuff, it serves a bit more like a support ability for the team to take these targets down. Which again reinforces Musketeer's role as a support. And bleed opens up some synergy with bleed-characters.
Also, it only makes sense to fire this type of shot a bit closer to the enemy, thus you can use it a bit closer (from rank 2).

Now there is a possibility of taking just a Buckshot instead of both Aimed Shot + Call the shot, since it doesn't gain anything from the mark (without trinkets), for some type of a more shotgun-frontline-support build. More on this later.

Patch Up

• Does slightly less healing
• But finally does cure bleeding (as it should IMO)
• And now can be used from 4/3/2 rank (from only 4/3) to support the Buckshot build.
  

Smokescreen

• Does no damage
• Stun targets at 3-4 ranks
• Has only 3 uses per battle
• Debuff now lasts for 3 turns (from 2)
• Debuff now decreases 20-25 ACC(from 15-20)
• Now can be used in 4/3/2 rank (from only 4/3) to support the Buckshot build
  

At first, I made it work the same as PD's Blinding Gas - same stun, same 3 uses per battle. But now I see that even tho It's actually strong by itself, it doesn't quite complement Musketeer as much as I thought it would.
Stun works only for 1 turn and then gets resist for 50% - so you normally wait for that one turn and do something else (except for Occ lol) - so you waste half the time (stun - something else - stun - something else) and with the Musketeer's kit its not really efficient. Yes, its strong, especially for someone like Plague Doctor that can stun - blight - stun, etc etc and it's okay, it's his role after all - but Musketeer is more focused on actually taking down those targets - especially under the mark. So then you also waste the mark's uptime by throwing stuns instead of the shots.
The problem with the vanilla Smokescreen was that it's just has been bad - too short, weak and the Musketeer herself is just too slow to be able to debuff enemies before their turn - like the PD would. So it's not even worth wasting time at this point and better to start shooting them.
So yeah, it needed some buffs, and the more I think of it - by being properly buffed, this skill could actually fit better than a stun. Design-wise, theme-wise and just by the tempo of the character. Now that the Musketeer is somewhat faster - sometimes even fast enough - to be able to debuff enemies before their turn - and with the obvious buff to it's duration (to 3 turns from 2) - you only waste 1 turn on it - for 3 turns and IF it causes the enemy to miss just 1 turn out of 3 - it's already better than a stun. Not even mentioning that it also lowers their Crit chance + damages a little. So I just buffed it. I hope that's enough.
Skeet Shot

• Now (should be) a guaranteed hit
• Now guaranteed healstress
• Healstress now also uncludes Musketeer herself
  

So it's basically the same, I just fixed some weird possibility of the enemy to dodge a fuckin light in the sky lol (just by giving it a lot of extra ACC, since i dont have any idea how to make it an actually guaranteed hit - someone with more knowledge on this pls hit me up).
And made it at least somewhat useful outside of cheesing some bossfights with Stun and Mark cleanse, by giving it a guaranteed stressheal, which reinforces Musketeer's support role with akin to Jester's stressheal (the same 4-12 stressheal), but this one works on the entire team. Which is better for having something like Abomination on your team or certain encounters where everyone gets stressed, but can't really help one guy that gets dangerously stressed.
And you are giving up one skill slot just for this purely support ability, so it's kinda balanced, if not weak, still.

Trinkets

• Wrathful Hat now only takes 33% Healing (from -50%)
• Second Place Trophy - +35 Debuff +35% Bleed +20% Healing +15% Stress
• Silver Musket Ball - +10% DMG + 8% Crit
• CC Set - +20% DMG vs Mark + 15 ACC vs Mark
• Icosahedric Musket Balls - +20% DMG +20% IgnoreProt +10% Stress
• Sturdy Boots are now Scouting Boots - +10% Scouting + 10% Trap Chance
• Vengeful Boots - +20% Bleed + 3% Crit
• Medic's Boots - +33% Healing Skills +20% Healing Skills at camp
• Bull's Eye Hat - +8 ACC +5% CRIT -1 SPD
  
  

So, all in all.
She's a much better character now both as a sniper and support. Still has a mark synergy and relies on positioning, so she's still a bit worse than other DPS like Grave Robber or HWM, which dont require much of a set up/conditions/positions. (Well, that's why mark teams are just worse. Too slow and not as flexible. But now at least, the pay-off and utility is better)

• She's better as a stationary DPS on the backline, doesn't need to move to deal damage, and now has a way to get back into her position with a Sidearm.
• She's better at focusing priority backline enemies, but still requires more actions for it.
• She's better now not only as a pay-off, but also as a set-up and support character, with her unique marks, debuffs and now also stuns and stressheal.
  

I've also tried make her other skills to be more viable and worth considering taking, so it opened up her for two builds - Sniper build with the Aimed Shot and marks, and the Buckshot build - without marks - focused on the frontlines.

So she's all around better character now, but still not nearly as broken and strong as some other DPS. Now she's just a decent DPS/Support character with a focus on the enemies backline, as devs intended her to be.
Well, i hope it is. Feedback appreciated.

P.S. I play with the "Musketeer Replace Arbalest" mod, because I much prefer her over Arbalest, especially with this rework. Arbalest as of now is unchanged, so i highly recommend these two mods together.
This is my first mod and I'm still open for some tuning - so let me know what you think.

Feedback request - tell me how you feel about the Smokescreen and if the damage pump feels right