Been looking through .xml files for something that would change weapon attack speed of an individual item or for a class/group of items. Is there such a variable?
Well, the stat requirements and defence value seem to be set in the “weapon.xml”, attack distance is set by the class in “weapon_class.xml”, weapon damage seems to come from the “melee_weapon.xml”. I can’t find a attack speed value anywhere, so maybe it’s a calculated value based on some other values or maybe (worst case and somewhat unlikely) hardcoded…?
The only way it can be done i know is by tweaking some of the rpg Params and with it the whole speed of combat.
I haven’t tested it, but it could be, that by changing the parameter only your enemys get faster, for as i understood, instead of making you faster with more skill, it makes your enemys slower.
Many of the are not set in the original rpg param
Here a list :
https://wiki.nexusmods.com/index.php/RPG_params_in_KCD
The standard values are given if you scroll down, though i recommend using the search function 
Propably relevant params:
AttackSpeedNormal
AttackSpeedNormalAgi
MaxAttackSpeedMod
AgiDiffToAttackSpeed
SkillDiffToAttackSpeed
I hope you find a way, as i currently do not have the nerve to test this, as the game is not installed on a ssd. But if Time isn’t a problem, i will get back in 1-2 weeks, and give you more info
Edit: Player around with AttackSpeedNormal and didn’t notice and difference, but that doesn’t mean there isn’t one^^
You can find a RPG parameters table with descriptions here:
https://wiki.fireundubh.com/kingdomcome/rpg-parameters