Questions

Does Judgment Blade by any chance ignore Protection for Critical?

It would be pretty hard for me to check. I believe it would. It's area of effect nature to me implies that it would, since it attacks multiple enemies, and if you crit one you crit all.

It's something someone with crit under 100 should check.

I know it ignores protection for damage, since I was able to hit food dungeon monsters for more than 1 without a large table knife of glewyas weakening them.

Edit: Ok just confirmed it ignores protection for damage, as I was able to crit food dungeon mobs without having them be weakened first.

Hm, interesting find. But it doesn't seem to ignore Defense stat; I was doing 500s on the ingredients and 2.5ks on White Spiders, but I didn't thoroughly test enough.
EDIT: Never mind, no it does not ignore Protection for damage; I hit exactly a 1 on ingredients that wasn't "tenderized". It only ignores Protection for Critical.

Might it be possible that the Apostle Defense Reduction is actually Defense Piercing? That is, Judgment Blade ignores Defense in calculation but doesn't reduce it whatsoever?

This is becoming more and more plausible to me as I go.

Breaking lies level 5 didn't seem to do anything for anyone else. It definitely doesn't reduce his damage reduction for everyone else, because no one else started hitting double damage.

I wouldn't be surprised if it turned out to be a typo/mistranslation.