This appears to be a medium shield made of high quality wood, steel, and leather, which will will radiate magic. If tested, it will prove to give its wearer a +2 bonus to both AC and all Saving Throws. It will seem light and unencumbering at this point.
Upon first being used in actual combat, the shield will become incredibly heavy, so much so that no character with less than an 18 Strength will have a chance of picking it up off the floor, and even if they can, the shield will be of no use whatsoever as a defensive tool, making the wearer fully encumbered. On top of all that, no matter what the victim's strength, they will be unable to take the shield off, as the straps will constrict tightly. Though seemingly made of leather, they'll be resistant to all attempts at loosening or cutting.
A successful Remove Curse will allow the wearer to free their arm. Severing the arm works, too, of course.