"These tight iron cuffs can fit over the wrists of any Large or smaller humanoid. When placed on a helpless humanoid, they make the captive more docile and compliant. The prisoner never attempts to escape of its own volition and agrees to any reasonable request unless it makes a DC 11 Will saving throw."
The way I would generally be inclined to read that strikes me as insanely overpowered for a 2000 GP item whose only spell requirement is Charm Person:
This can be used on anyone who, at any time, has the Helpless condition, which is comes along with being "paralyzed, held, bound, sleeping, unconscious, or otherwise completely at an opponent's mercy." Actually wait, side question there- "held?" You can't coup de grace someone your friend has grappled, can you?
Anyway, the important bit here- It is possible to get this manacles on someone if you manage to paralyze/pin/sleep them for... well, not even a whole round, just long enough for your friend to slap them on, which I believe would just be a standard action.
At that point, it seems 3 clauses activate:
A- "They make the captive more docile and compliant." Open to some interpretation, but at the very least, I'd figure that would instantly end a barbarian's rage if nothing else.
B- "The prisoner never attempts to escape of its own volition." Hugely open to interpretation. At the very least, this seems to clearly indicate that there is absolutely nothing you can do to get the manacles off. I could additionally see it covering: Escaping from any other form of bondage (rope around your legs, bodily strapped to a horse, etc.), attempting to flee, even without being otherwise prevented from doing so, or attempting to in any way harm the person who slapped you with the shackles or their allies. That much would seem to cover the basic intent of the item ("Is there some magic item we can use to get this guy back to town without having to deal with him constantly taking 20 on escape artist and making us knock him back out?") I could even see the argument made that you can't even say, use message to explain the situation to your friends if you really wanted a broad definition of escape.
C- "[The prisoner] agrees to any reasonable request unless it makes a DC 11 Will saving throw." I want to say this much is pretty clear cut, but... reasonable request actually is pretty vague under these conditions. If someone is your unwilling captive, the argument can be made that it isn't reasonable for them to go along with any suggestion you make. Particularly since said suggestions would most likely be along the lines of pressing them for information about their allies, or marching themselves off to face a higher authority. Especially considering they're powered by charm person, which, if cast by itself, would end immediately under basically any conditions that would lead to shackling someone.
B is the real sticking point here. This isn't really a low level magic item you can use to completely render someone a completely docile captive who will stay out of all combat, with no save other than the one to avoid whatever condition left them helpless enough to pop them on, is it?
I don't see a problem with this. Helpless people are generally dead anyhow. This provides a nice RP method to deal with bad guys that does not involve death.
Note: Held is NOT Grappled. Held is synonymous with Paralyzed via Hold Person. Honestly, I think it is a holdover term from previous versions that is no longer used in any other context.
BTW, Pinned (a more severe version of Grappled) does not equal helpless either. It takes being pinned and THEN bound to result in helpless.
- Gauss