Which is better?

Okay, I have a Dragon slash Claw with 90 weapon attack, no slots(unhammered) and is an ''Epic'' item, the buffs it gives me are: ''4% Crit Rate, Ignore 15% of the targets Physical/Magic ATT when attacking''.

And a ''Rare'' Fangz, with 90 weapon attack, and a +5 weapon attack potential(the other buff is stupid).

Does the ''Ignore'' apply do PDR rate, or does it just do it to their Vanilla defense? I want to know before I start cubing it some more. (Please don't lecture me on my Dragon Slash claw that isn't a unique 9999999999999999999 attack claw).

Yes, "ignore" is from PDR - so a monster that had 10% PDR will only have 8.5% PDR when you attack with that claw (note that it multiplies, not subtracts - 15% of 10% is 1.5% less pdr).