I think there's a bug with interactions between "What a Rush" and +Constitution items.
My Rogue decided that 5 CON is truly terrible for a melee fighter, so I bought a couple things from Anna with +1 CON.
I was at 131/131 health and replaced my Source Hunter's Armour (Armour 3, Movement +0.14, Initiative +1) with Mighty Leather Armour (Armour 14, Movement +0.30, Initiative +1, Constitution +1).
Before, my AP was 12/9/7 Max/Start/Turn. AFter just putting on that new thing, my AP was 15/9/9.
Looking at it, it said my maximum was Base: 7, Con +6. My Turn AP was Base 4, Spd + 3, and it also had a mystery +2 bonus. It was adding in the +2 from What a Rush, even though it wasn't active at the time.
Even counting the change to my health pool, I was well above the 30% threshold where the Talent should have taken effect.
