taking on hard falz

[Hrith]

But if the slash does a set amount of damage isn;t the armour useless?

it is, that's why against Falz, you should use armours with good resistance and do not regard defense or evasion, Attribute Plate and Attribute Wall is an excellent choice.

if you cannot survive the swipe, use HP units or HP materials, if needs be, Lv until you have enough HP since it's the only thing that can save you.

none of Dark Falz's forms use physical attacks, so DFP is completely useless.