Here's the newspost with relevant information.

Originally posted by drgentleman

Cool lemme just update the wiki with this info now that we suddenly have it 8 years later

It's already known and matters mechanically that: a) Armour is applied when calculating the damage of the hit, before that damage is used to determine stun. and b) Block removes all the damage of the hit after stun is calcualted, and does not affect the stun duration (but changes the animation played for that duration from the stun one to the block one).

That imposes this ordering.

This is something anyone could already have concluded from known info, it just didn't really matter before, so most people hadn't considered it.

Originally posted by ClemPrime13

Block happens before armor, so it’ll block 50 percent, then the rest of it hits armor and is reduced.

Block happens before armor

No it doesn't.

Originally posted by Escaridole

I wonder if stun for the blocked hit w/this keystone would be based on the original damage or the halved damage? That could be another big difference, for the handful of people out there not playing with stun immunity

Without this keystone, block already prevents all the damage of the hit, without affecting the stun.

Preventing less damage isn't going to make it better and stun prevention - blocking just doesn't affect whether a hit stuns, it only removes the damage (or in this case, some of it).

Can you PM me your account name?