For PLD,

The weapon is 2 weapon damage, 6 str, 8 vit, 6 det
2 weapon damage = ~18 str.

Going from i180 chest to i200 chest gives you 15 strength, 19 vit, 64 def / mdef.

I don't know the mitigation the def will give you but 11 vit and the ~160 hp that gives you isn't going to save you from anything.

With how bad PLD's enmity generation currenty is, you need all the help you can get. So the weapon will not only add what it inherently does to your DPS, it will also allow you to Royal Authority more.