What does the damage formula look like?
You can find it on the discord, I think
epeli posted it ages ago, I have it save in a .txt. For weapons it's: baseDamage*(skillMod+strMod-1)*passiveMods*critMod*specialMod
baseDamage is base weapon damage. Skinner for example modifies the quality of leather, thus increasing the base damage of crafted gloves. Same for guns with Gun Nut.
skillMod is damage bonus from skill.
strMod is damage bonus from STR, applicable for melee. Unarmed used to have strMod as a separate multiplier, but it may have been changed in the recent patches.
passiveMods is stuff like TfB, Opportunist, Blindsiding. Additive with each other, so in case of melee, with 10 stacks of TfB, out of stealth and against an stunned enemy this
should be 1.9.
critMod is crits.
specialMod is for conditional special attacks. Ranged weapons only as far as I know, so for Snipe, Aimed Shot, Kneecap etc.
If not a crit, Expertise is then slapped on after all that.
Stuff I'm not sure about:
Expert Unarmed and the veteran feat are both fucky, not sure where they fall in the damage formula, probably passiveMods.
Heavy Punch and Combo - sometimes I'd get inconsistent results, might just be that my math was wrong and they're passiveMods.
Concentrated Fire, it's a debuff, so it may work by increasing the mech damage modifier on the effected enemy. Or it might be coded to work in some other way. You never know.
Spear Throw, personally never did extensive testing, someone on discord might know more, probably gets added to passiveMods.
Never did extensive calculations for psi damage, since there aren't that many conditional bonuses, and few psi specializations offer damage bonuses, so I never bothered to learn how they stack.
But from the time I played a TC NO specialist, I remember that the damage bonus from Cerebral Trauma is added to the damage bonus from headband NO filter. So they might be treated as passiveMods for psi?
Dunno how exactly Corporeal Projection stacks for PK spells, the feat might just enable strMod for the affected spells.
I use this as a reference mostly. There are oddities and outliers and without looking into the code it's hard to be sure.