if we’re talking FE8 i already made a thing for that
i originally set it to item might
+ unit's' mag
but you can just change the pointers in the event file to make it res instead of mag and remove item might entirely if you’re not into that
assuming that you want healing to be based off of only res you can change that part that says
//stuff that modifies the heal amount
POIN 0x80175DC //get item stat to add to heal value
POIN 0x80191B0 //get unit stat (mag) to add to heal value
WORD 0x0 //for stuff like skills
to
//stuff that modifies the heal amount
WORD 0 //get item stat to add to heal value
POIN 0x8019270 //get unit stat (res) to add to heal value
WORD 0x0 //for stuff like skills
and then apply the change with EA
this overwrites the old thing for healing so it doesn’t take up any free space