Was messing around with some duels last night and I noticed Evsicerate logging twice in my combat log.
If only find weakness was up, no rupture, no stun, etc. After using a single eviscerate, this is what the combat log showed.
Eviscerate hits target for 996.
Eviscerate hits target for 997 shadow (critical.)
What mechanic is causing the shadow damage?
When I did an eviscerate with no modifier, such as find weakness. there was no shadow damage.
Is find weakness the shadow damage?
Also, prune orcs please. I hate dueling orcs as sub rogues in a mirror. The stun reduction is so infuriating.
That’s from rank2 Eviscerate.
Yes, (I think its somewhere in the tooltips) and its been on some blue posts and wowhead.
Can confirm that while find weakness is active, eviscerate does 50% additional damage as shadow damage.
Ahhhhhhhhh ok thank you. Lol. I haven’t looked at a combat log in a long time so I was like wtf 2 eviscerates?
I did notice some inconsistency with the shadow damage. Like if my evsicerate was buffed by NV the shadow component didn’t scale accordingly IIRC. not that subtlety needs more damage right now.
The night’s vengeance hotfix is probably held together by duct tape. Since it works by consuming the buff, the script is probably listening for then modifying the first Evisc event after the damage for both has been calculated.
Yah. This is the part of Find Weakness that I really dislike. I don’t think it adds anything. It just makes using Eviscerate while Find Weakness isn’t up feel really bad. 
Yeah. Why am I doing shadow damage anyway lol. Just give me expose armor or proper find weakness. What was wrong with bypassing armour without magic.
What if they have high shadow resist and now I can’t bypass that? (assuming shadow resist existed.)
it’s just dumb
You know, that is a good question. I wonder how the shadow portion interacts with things like Cloak of Shadows and Anti-Magic Shell. Or any other damage reduction ability that applies to magic only. I do know that in general, physical/magic hybrids can cheat the system. Like, you could apply Nightblade to a Rogue who had Cloak of Shadows active. Even though Cloak of Shadows removed Nightblade. However, Anti-Magic Shell did stop Nightblade from being applied.
Then there’s also Blessing of Protection/Spellwarding. How does it interact there? Will the shadow damage go through BoP? Will it go through Spellwarding since it’s applied via a physical attack like with the Cloak of Shadows-Nightblade deal?
We need answers!!!
It’s also interesting because you can (or at least used to be able to.) cloak, spell reflect, and ams etc Cold Blood. but that’s more of a direct spell effect. So is it also happening to our shadow stuff? 
That interesting. Cold Blood should follow the same rules Nightblade does since it’s applied via a physical attack. So, you shouldn’t be able to Cloak of Shadows it, at least.
Granted, Cloak of Shadows does have a mechanic where for like 0.1 seconds or something upon activation you are immune to all magic and even Gloomblade and Nightblade would be immuned. Even though post that, you can freely Gloomblade/Nightblade the Rogue. I did see that a few times since I’d wait for the Rogue to pop Cloak of Shadows to throw up Nightblade… Or just while spamming Gloomblade.