question about free action opcodes (bg2ee)

i am not a modder, but i have little experience about how to create or modify items in the original game.
in the next future i want to try to modify for ee the flail of ages +5 and the ixil spike +6 to make their free action allowing a toon welding them to be improved hasted.
i know that some players don't like that feature and to upgrade a weapon to have it somehow less useful for some of us makes little sense.
i should be able to do the thing, to extract the weapons from the game, change the opcode and create a file that every willing player can drop in its override folder, but knowing which opcodes give free action and in which way they operate will make my work easier. i lack of the knowledge to look at the game files and determine how each opcode works, mine is a more trial and error approach.
i know that i can simply use the opcode used for arbane's sword, that makes the welder immune to hold person, but having knowledge of all the possible opcodes, and of all the effects caused by the opcode used for foa and ixil, would make me able to do a better work, maybe creating more then one file, form the basic one using the basic boost of arbane to a weapon that gives all the benefits of the upgraded foa and ixil without preventing free haste ( i maybe have to stack opcodes to obtain it, but i suppose i can handle it) so a player is free to chose if trading the capability of being improved hasted with less protection or to have all the advantage of the actually used opcode without the disadvantages.

if someone can provide here the list of the free action opcodes and what exactly each one does it would be much appreciated. i don't think that i will never become a true modder, but i would like to give my little contribution to the modding community this way.

thank you in advance.