I was working on another project, and noticed a problem concerning slimes.
first, I was using all blank equipment, level 100, quality 25%, zero stat and hero point, greed for all natures, and had Twister on all 4 Wizard weapons, with Arcane element. also, I was using a blank fairy and shock slime for comparison testing.
what I found out was that the shock slime’s 10% shock damage bonus was working on the Arcane element weapon, but when I changed the weapon to shock, the damage wasn’t getting the 10% boost. I tested if for all elements, and Arcane was the element getting the shock 10% damage bonus, not the shock element.
as an example, for wizard sword, the Pierce damage per hit is 6562. + 10% is 7218. the shock slime was boosting arcane element to the 7218 damage, but any other damage was 6562, even shock.
when I was done testing this out, I wondered if the 100 shock resist was working. it was not showing up on the defense page for shock resist, even though the item element resist was showing up. the one that gives item level /2 in elemental resist.
Edit: rewrote title to be less frivolous.
interesting… hmm
I know. I had written in another post about some ways to use the slime bonus damage. I mean, you are getting 6 affixes, plus another free 10% damage bonus to a certain element. not too bad. and then I made this unsettling discovery.
update: recently I got some Legend Slimes, and I started to wonder if the Pet Slimes Elemental Bonus is a hidden damage boost. I know the damage boost boosted the Arcane Element, but one of the Pets I found was Aether, so I am going to do a new round of tests and see what new things I can discover. (Aether gives a 10% boost to Arcane Element damage)
Another Update:
5 slimes with different Elements. Arcane, Fire, Ice, Poison, and Shock.
1 Fairy.
all pets normal, with no affixes.
1 Staff, no affixes, level 100, 25% item quality.
when the Staff had Arcane Element, damage with all pets is 7687 per hit. this is .9525% less then the other Elements.
when the Staff had Fire, Ice, Poison, or Shock, the damage with all pets is 8071 per hit, except for the Poison Slime with Staff Fire Element. damage per hit was 8879 for some reason.
I’ll have an edit later, I need to check the damage ranges against monsters to see if the 10% damage boost is shown while hitting monsters. I did a trial run, but need to check out some numbers before posting.
for some reason these numbers are the opposite of what I did in the original post, so now I am officially confused. 
one more update:
I wanted to check the damage range of the staff I was using with the fairy and slimes, in case the 10% damage boost was showing up in the battles. it looks like the slime damage boost isn’t working. I was getting the same damage ranges with slimes as I was getting with the fairy.
thank you all for being patient with me and putting up with my multi post.
it seems for now, that the only slime pets worth using are the ones with Set affixes, unless you really like having a slime pet instead of one of the others. hopefully, the slime pets boost ability will be corrected soon. and no, it doesn’t need to be fixed during the Holidays. 