Guild Wars 2

I’ve been soloing SEp1 and at Tazza, I’ve been trying to get my phantasms to survive her Mind Stab. It doesn’t seem to be working and something seems fishy.

So here’s the data:

1. Mind Stab does around 6000 damage to me: 5958, 6034 are a couple examples from my combat log.
2. The wiki says that my illusions have the same armor as my mesmer so they should be taking around 6000 damage from Mind Stab as well.
3. However, my mesmer has 11082 health in the dungeon (level 65), which is 69% of my level 80 health.
4. The wiki says phantasms have 5969 health at level 80. Assuming phantasms downscale the same amount (69%), that means they should have 4119 base health in the dungeon.
5. With Signet of Illusions (+ 50% health) and Persisting Images (+ 20% health), they should have 4119*1.70 = 7002 health in the dungeon.
6. But 7002 health means my phantasms should be surviving Tazza’s 6000 damage Mind Stab. They’re not.

So what’s wrong? Is some of my info wrong, or did I interpret something incorrectly? Or is there something wrong with Signet of Illusions/Persisting Images?