Alright, so I’ve done a bunch of number crunching on this because I was really curious about it.
I took my force sword and experimented with using the Psy Wrath talent (or not) and checking it against the impact of having different warp charges.
Cutting to the chase, I believe it’s mostly working as intended (i.e. NOT broken).
The reason why you’re seeing a lower % increase from Psy Wrath is because Psy Wrath scales from 5 - 15% damage from ZERO to 100 peril. Meaning if you take the take feat and have zero peril, you get an immediate 5% damage buff. So if you’re calculating the % increases, you need to make sure to turn OFF the feat to get a baseline damage number and then check damages as your peril goes up.
So for instance, I tested my numbers on a Scab Mauler (Flak Armor, body hit). With no talents and warp charges I did 52 “base” damage. Turning on Psy Wrath feat, this immediately raised damage up to 55. This is as 5.77% increase, but if you back calculate a clean 5% increase the expected damage would be 54.6, which the UI is just rounding up to 55.
So in the chart below I ran numbers for 0 - 4 warp charges both with and without the Psy Wrath feat, and also looked at the effect of high peril and Psy Wrath with 0 and 4 warp charges.
Psy Wrath at 97% + peril and 0 warp charges resulted in 15.38% damage increase over the base (52 → 60 damage). With 4 warp charges, it was a 25% increase (52 → 65 damage).
The one thing that seems off is that my expected numbers track well for everything except 4 warp charges, where the actual number was a little below the expected. With 4x Warp Charges and 97%+ peril, you’d expect 67 damage, and I only 65. The other calculations, rounding up or down as appropriate, tracked correctly. This could be something to do with how multiple warp charges stack and the means of calculation - but it doesn’t seem too wildly off.
EDIT: Updated to include warp charge levels 5 and 6
The other thing I couldn’t figure out his how I ended up with 52 damage on the mauler in the first place. The weapon tab says I should be doing 47 damage to flak armor on a light hit. I don’t know where the 52 is coming from.
By the way, the weapon’s reported damage, at least for the force sword, is the reported damage stat % (in this case it’s 48.45 with my weapon at 79% damage rating) multiplied by the first target stat (which provides a 1.3 multiplier based on my weapons rating). So the “damage” number you see at the top of the item card is “63” - which is the same as what you see reported as the damage in the detailed hit breakdown for unarmored. Flak is listed at 47, so again, no idea why it’s going up to 52.