From my testing on the beta, nothing has changed with weapon armor penetration from the posts above. An enemy with 50% DR hit with a weapon that has 50% armor pen will reduce the incoming attack by only 25% (50 dr * .5 armorpen). There are a few more enemies now with higher armor so keep this in mind before picking up a 0 armor pen axe.

I’ve already noticed another multiplier on top of combo multipliers for Heavy attacks. Example: Axe’s 1st HA is clearly stated at 1.2 in the patch notes but I’m getting 1.3 - 1.36 with a lvl 0 character. Super fun stuff there, but might be a bug?