High heal classes such as Pallies and HPs will just be huge tanks with IW + 2.8-4k heals using Bascojin + Kiel.
If HP uses two Kiels, they will have no offensive power at all. I think this is a fair tradeoff. I dont know about Palis though. They have always had super high survivability mixed with very high offensive capability and support.
That's the defenition of broken. Valk Helm [Kiel] and Mini Glasses [Kiel]; the only loss of power you face is -20 int and the -20 dex loss; but it's not a big difference because with Bless [+10], 2x Sting Bry [+18], Evang [+20], Job Lv. bonus [+9] = + 57 dex, meaning you'd need 93 dex for IC, and distribute the rest between Int and Vit (not much though because of Valks +20 vit).
Priests won't suffer a big loss swapping from kaho to Kiel Valk Helm.