So, are there any rules governing the use of a single magical bracer/gauntlet/eyepatch/boot?
I'm aware that most magic items come in pairs, and their effects logically come from both parts simultaneously. But what about items that seem to be just a single item (e.g. seducer's bane bracelet)? Is this a single bracelet? If so, does it take up both wrists' "slot?" Or could you conceivably acquire a second single bracelet/bracer/etc?
Cheers.
This device is a single leather glove. On command, one item held in the hand wearing the glove disappears. The item can weigh no more than 20 pounds and must be able to be held in one hand. While stored, the item has negligible weight. With a snap of the fingers wearing the glove, the item reappears. A glove can only store one item at a time. Storing or retrieving the item is a free action. The item is shrunk down so small within the palm of the glove that it cannot be seen. Spell durations are not suppressed, but continue to expire. If the glove’s effect is suppressed or dispelled, the stored item appears instantly. A glove of storing uses up the wearer’s entire hands slot. The wearer may not use another item (even another glove of storing) that also uses the hands slot.
I don't know if this is a universal rule, but it's how I would rule for it (you only have 1 "wrists" slot after all).
If someone contradicts this convoncingly enough I could change my mind
You only have one "wrists" slot regardless of what takes up that slot and regardless of how many wrists you have. While some "wrists" slot items are paired and some are singular, wearing such an item (or item pair) occupies the slot; you cannot wear another and gain the benefits. The effect would be similar to attempting to wear more than two rings--additional items in the same slot simply fail to work.
At best, you might be able to wear a bracelet on one wrist to get the effects, wear a glove on the other wrist to no effect, then when necessary remove the bracelet to simultaneously deactivate the bracelet and activate the glove instead. Whether that actually works is a pretty grey area.