Normal stat damage is Mainstat/8 with .25 in Base and .5 in Random, for purposes of averaging damage, we shift it all to base making it Mainstat/16, which for the old stat cap of 200 produced 12.5 stat damage that equates to 38.5% melee.
LS is 3/8 at a 10% LS rate shifting all to Random, for purposes of averaging damage, we shift it to base making it 3/160 which produces 3.75 stat damage that equates to 11.5% melee.
LS damage is a type of stat damage that is added on to the same equation as weapons' base and Mainstat damage, LS boosts are balanced around the standard LS rate of 10% and apply specifically to LS stat damage only.
Due to our pet receving an LS update, the Devs should have reviewed that the monsters do indeed gain the .4 LS from not having a pet.
As long as Luk is not at zero points, the engine wil enable a roll for LS occurrence, and yes negative LS does exist, it subtracts damage.
Stats points invested in any stat receive exactly that much of a portion of the stat's power at cap. Its not an all or nothing scenario, while 5 Luk may not do much at least for initiative, it gives exactly 5 stat points worth of LS damage averaged, BtH and combat defenses.