Astaroth600, I think Akihiro is distinguishing Bodyshop accessories (e.g. a pair of glasses whose shape and texture has been altered to look like a sword) from accessories such as the handheld "Primp" mirror which is an object snapped into a hand slot.
There are examples (user-made and EA-made instances) you can look at where objects are snapped into the body slot(s) the compose the hand. You mentioned some. If I recall correctly, sometimes objects snapped into these slots are automatically deleted (not permanently, just the particular instance of the object) once the interaction is complete.
You would need to create the object and the means (i.e. an interaction) to snap the object into a body slot. Here is some information on the Body Slots.
I don't mind if you call me "MSD" or something for short. Tumblr