In 1.12.2 regulations, the reason why Fire knight's greatsword have damage level 3 is that Fromsoftware forgot to add behavior id so it was using default value of colossal sword which is 3. This also cause a problem that it needs 3 hits (the full chain attack) to gain successive attacks buff.

In 1.12.4 update, they fill in behavior id from 100420000 to 100420420 so it can use correct data of Godslayer's greatsword.

Two regulations modification offered here:

Prev : Added behavior id are all deleted. So this version means it is fully rollback to previous version.

Plus: Damage level of the whole motion of Godslayer's greatsword increased to 3. (Note that this also affect Godslayer itself, so double W
This version means stagger level rollback and it only need 2 hits to gain successive attacks buff, which is obviously a great improve. :) But colossal sword sucks in this dlc so why not?

I will not update this mod afterwards so I want to share how I did this so everybody interested in can update themselves:
Prev: Delete behavior id from 100420000 to 100420420.
Plus: Atkparam_pc 404000 404010 404020 404200 404210 404220 404400 404410 404420 (light atk chain) 402100 402105 402300 402305 (heavy atk) modify their dmglevel to the value you want. What I have done was changing all of 2 to 3 here.

How to install: rename one you want to regulation.bin and replace in game folder