Broadstroke Unique Quiver - 30% physical damage?

Comparison

Broadstroke Quiver:
adds 1 - 4 physical
30% increased physical damage
10% reduced enemy stun threshold
21% increased stun duration on enemies

Heavy Quiver:
adds 1 - 4 physical

Blue Heavy Quiver:
adds 1 - 4 physical damage
adds 6 - 9 physical damage


Main hand physical damage:
no quiver: 172 - 438
Broadstroke: 189 - 487
Heavy Quiver: 176 - 454
Blue Quiver: 200 - 491


To me it seems like the Broadstroke's 30% damage isn't adding 30% of my main hand physical damage. It is adding something though, as the damage is higher then the base Heavy Quiver.

The math is probably correct in there, and I'm just not getting it. For being a unique item though, i figured it should be better then it appears to be - as a blue item with only 6-9 extra damage being better then it is kinda lame.

Thoughts?

The important detail will be what other increased damage % you have applying to your main hand physical damage.

For adding 7-13 damage to effectively add 28-52 damage, you must have around 300% increased damage, meaning 30% increased damage is increasing it from 300% to 330%, only a gain of 10%.

Edit: By my attempts to put the values into a spreadsheet and trace it back to be consistent with the other values given, your Broadstroke damage should be 191-490. Which is close enough that I assume the discrepancy is from compounded rounding errors because I can't actually see your full modifiers.

Thanks for the clarification :)

It makes sense with the math laid out, but still sucks that one of the few unique quivers out there doesn't seem to do much at all.