Widowhail and Pathfinder concoction skills - detailed report

Widowhail (and similar passives for quiver effect) interact in unintended ways with crit multiplier.

Numbers are from https://www.youtube.com/watch?v=cvxAgmzaCdw - credit to Path of Evening for the build and video.

At 7:44, Path of Evening displays his skill sheet for Fulminating Concoction.

The listed average damage per hit is 83924.72, but the main hand total damage is 10116-36038 (average 23077). This means the effective multiplier from crit is 3.636725. Further down, there's a main hand crit damage bonus of +434%, but also strangely an offhand crit damage bonus of +1884%. If you average these, you get +1159%, and then multiply by your crit chance of 22.75%, you get +263.6725%, or a multiplier of 3.636725. In other words, this erroneous offhand crit multiplier is being included in the calculations as if hitting with a main hand and offhand at 50% weight each.

What I believe is happening is that the character's crit multiplier is applying to both "hands", but then the game considers the offhand to be the quiver, and so Widowhail and the passive tree nodes are multiplying this crit multiplier. This results in inflated damage numbers for concoction skills with this Widowhail setup.

I'm not sure how much you're commenting on the insane crit dmg levels on the offhand or not, but this is the case for normal dual wielding as well.

It seems like offhand crit dmg is being calculated by squaring the mainhand crit damage number. That is, if you have 400% crit damage bonus for your mainhand, your offhand will be 400% x 400% = 1600% crit damage.

I tested this in how it applies to actual damage while dual wielding, and it does precisely what the tooltip says - when swinging with both weapons, one of the two hits will crit with the normal 400% crit damage number, and the second one will crit for 1600% crit damage, resulting in RIDICULOUS crit numbers.

Just adding on to your post, noting that stuff like this is happening beyond just concoctions.