Not the grey owlite shield of course, let's talk about the armor.
Normal+elemental defense plus fire+shock resist, how is that bad, come to think of it?
It's like you lose only sword and bomb bonuses when compared to the competing sets, trading those for a shock resist. I note that in FSC, shock hardly matters, but knights get shocked in all arenas.
EDIT: WHOOPS, meant Grey FEATHER Set. Fix'd.
Negative stun resist can be really bad. You're not going to get stunned too often (lumbers don't hit you all the time, right?), but when you DO get stunned, it's going to suck. Also, some people regard Vog Cub's ASI superior to the shock resist you get with Grey feather.