Just now, I picked up an item of clothing that is +1 Mind-affecting *and* Hold Person Immunity. The only other HP Immunity gear I've seen was a smallshield with no other bonuses, as one of the Gobsquat permadeath tournament prizes.
Now since HP is the weapon of choice for grabbing anyone usually, immunity to it seems pretty damn strong if you're, say a Rogue wearing this thing. I'd not mind if it came with drawbacks like HP Immunity but at the cost of lowered Will and Fortitude saves so that the tradeoff is other stun spells are more likely to hit. Spell Immunity can't be defeated by anything. Give it Mind Blank charges or 1/day Clarity or something, but not a permanent immunity without some big drawbacks.
This thing is DM loot grade good. It makes the old Ranger +1AC boots look bad, and those were nerfed. Immunity to Acid Arrow, Acid Breath and Acid Splash would be less unbalancing and still flavourful.
Pretty shabby protection against a sword, arrow, axe, fist, bite, claw, staff, fireball, electric shock, and just about every other attack out there... If I recall, it is cloth? It is only useful for one possible situation, that is planned. Assassinating a wizard, or perhaps a cleric. I can see why you would want it nerfed..but I think it is a nice addition. Just mho tho..
It's been available since forever and I don't think I've seen it actually used -once-, much due to, as Crod mentions, it is cloth, and its use is highly limited.
It also looks retarded and we get a kick out of wizards wearing something like that around. :)
It's not OP at all. It is good however.