Coat of Arms, A System-Agnostic Magic Item

Coat of Arms

Description:  This voluminous leather duster is inexplicably furnished with four sleeves.  Anyone trying it on will find themselves sprouting arms to fill any "extra" sleeves (usually two, but amputees will be getting extra benefits) for as long as the coat remains fastened.  It will fit comfortably over all but the bulkiest of armor and the magic involved will temporarily modify anything worn beneath it to accommodate any changes in physiology.  All alterations reverse themselves if the coat is removed.  Magical senses will reveal a strong aura of transformation magic. 

Powers:  Mechanically, having an extra pair of arms won't grant extra attacks or spellcasting ability but will allow the wearer to perform noncombat actions more easily.  You can attempt to climb while still wielding weapons, perform sleight of hand tricks, use potions or oils on yourself, or anything else the GM agrees to.  You can also hold more items at once (although you maximum carrying capacity remains the same) and reloading crossbows or similar ranged weapons becomes much easier.  All extra limbs are treated as though they were part of your normal allotment of limbs, so they benefit from strength enhancements, suffer pain and injury if damaged, and share quirks the wearer may have like ambidexterity, double joints, etc.

The coat will also let you wear two sets of magical gloves at once, but not extra magical rings.  Beware though, items currently carried or worn by "extra" limbs will simply vanish along with them, reappearing only when the duster is next put on and fastened - which might not be by the same person.

Possible Origins:  The first Coat of Arms is reputed to have been a gift from the eccentric Qing of Quun to a favorite jester, but others have since duplicated the enchantments involved.  The extra sleeves on these items make it difficult to disguise the item, but some adventurers, thieves, and thieving adventurers have used trickery or other magics to conceal them for various questionable purposes.  

Complications:  If the Coat is removed all extra arms will disappear, carrying any items (but not creatures) carried by them into temporary non-existence as above.  If all the sleeves of the duster are turned inside out it simply won't function, even if worn inside out.  If only some are inverted and the Coat is put on it will disappear with a dreadful ripping sound, lost to all but the most powerful magics or divine intervention and taking its wearer with it unless they succeed at resisting potent magic (in D&D terms, save vs. Magic Item at -4).   

Design Commentary:  This is another "rescue" from an old comment of mine on Telecanter's Receding Blog - which sadly seems to be on hiatus - with some minor changes.