Probably some of you have noticed this already. These items can be slotted to multiple equipment spaces, there is no secret there.
Shackles - Wrists, Feet
Five Rings - 1st Finger, 2nd Finger, Trinket
Chains - Neck, Waist
However, when it comes to hotbar them or double click them in the inventory window, they will always go in one specific slot as it follows:
Shackles - Wrists
Five Rings - Trinket
Chains - Neck
Thus, the only way to put Shackles on feet for example if you used Cannith Boots or FoM boots for an encounter, is to go back to inventory window and drag the Shackles on your feet. It's the same mechanic that applies to rings, all the rings going on the right finger slot whenever it comes for a swap.
My wonder is could there be done something about this? Can we be allowed to allocate each items in advance where should they go when equipped for example? Could this be implemented in a further fix/update? If not, then can we just have them go by other priorities? Like changing the priority for Shackles and making them go to feet instead of wrists, due to many FoM boots or Cannith Boots fans.